Optical apparatus

ABSTRACT

To provide an optical apparatus which controls an interface state to change a focal length by using an optical element having a container sealing first liquid that is conductive or polarized and second liquid that does not mutually mix with the first liquid with their interface in a predetermined form and electrodes provided in the container and of which optical characteristics change according to change of interface form due to application of voltage to the electrodes, and in particular an optical apparatus that controls a duty ratio of alternating current voltage applied to said electrodes for changing said interface form.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical apparatus including anoptical element utilizing electro-wetting (electro-capillarity), and inparticular to power supply means for driving the element.

2. Related Background Art

Of optical systems built into optical apparatuses such as a still cameraand a video camera, those capable of changing a focal length mostlychange a focal length of the entire optical system by mechanicallymoving part of lenses (or a lens group) comprising the optical system ina direction of an optical axis.

For instance, Japanese Patent No. 2633079 shows a configuration wherein,of a zoom lens-barrel comprising a first group of lenses moving in adirection of an optical axis by zooming, a first group of lens-barrelsmoving in the optical axis direction on movement of the first group oflenses and a cam barrel moving in the optical axis direction due tomovement of the first group of lens-barrels, the first group oflens-barrels fit an outer-diameter side of a fixed barrel, the cambarrel fits an inner-diameter side of the fixed barrel, and a front partof the cam barrel fits an inner diameter side of the first group oflens-barrels, and the cam barrel is moved in the optical axis directionso as to move the first group of lenses and perform zooming.

Thus, in the case of changing a focal length by mechanically movinglenses (or a lens group) in a direction of an optical axis, there is adeficiency, that is, complicated mechanical structure of the opticalapparatus.

To solve this deficiency, there is a case of rendering a focal lengthvariable by changing optical characteristics of a lens itself.

For instance, Japanese Patent Application Laid-Open No. 8-114703provides a varifocal lens wherein, in the case where hydraulic fluid isfilled in a pressure chamber at least one side of which is comprised ofa transparent elastic diaphragm, and the transparent elastic diaphragmis deformed by hydraulic fluid pressure exerted on the diaphragm torender a focal length under variable control, the deformed form of thetransparent elastic diaphragm is optimized so as to make lens aberrationless likely to occur, and also hydraulic fluid pressure in the pressurechamber is measured with a pressure sensor formed on the transparentelastic diaphragm so that, by adjusting hydraulic fluid pressure basedon that value, change of a focal length due to thermal expansion andcontraction of hydraulic fluid and so on can also be controlled.

In addition, in Japanese Patent Application Laid-Open No. 11-133210, anelectric potential difference is given between a first electrode and aconductive elastic plate to lessen the space between them by generatingattraction by Coulomb's force, and it consequently becomes possible, byusing a volume of transparent liquid excluded from the space betweenthem, to make convex and deform a central portion of the transparentelastic plate with respect to its back facing the transparent liquid.Then, a convex lens is formed by the convex-deformed transparent elasticplate, transparent plate and the transparent liquid filled between them,so that power of this convex lens is adjusted by the above electricpotential difference to constitute a varifocal lens.

On the other hand, a varifocal lens using electro-capillarity isdisclosed by WO99/18456. If this technique is used, electrical energycan be used directly to change form of a lens formed by an interfacebetween the first and second liquid, so that it becomes possible to makethe lens varifocal without mechanically moving it.

However, the above-mentioned related arts have the following problems.For instance, the above Japanese Patent Application Laid-Open No.8-114703 describes an actuator controlling apparatus for driving anactuator wherein, as the actuator, a unimorph mechanism by apiezoelectric element formed on a transparent elastic diaphragm isutilized. However, this known technique requires high rigidity of theelastic deformed portion, and consequently has a fault of requiringlarge amounts of electric power.

Moreover, the above Japanese Patent Application Laid-Open No. 11-133210also requires high rigidity of the elastic deformed portion, andconsequently has a fault of requiring large amounts of electric powerlikewise.

Furthermore, the above WO99/18456 can change optical power with smallamounts of electric power since there is no mechanical movable part, butthere is no detailed description of power means, and a technique forcontrolling optical power with precision and small amounts of electricpower is not disclosed.

SUMMARY OF THE INVENTION

One aspect of the invention is to provide an optical apparatus whichcontrols, in a short time and properly or in a state of reduced powerconsumption or in a state suited to a photography sequence, an opticalelement comprising a container sealing first liquid that is conductiveor polarized and second liquid that does not mutually mix with the firstliquid with their interface in a predetermined form and electrodesprovided in the container and of which optical characteristics changeaccording to change of interface form due to application of voltage tothe electrodes.

One aspect of the invention is to duty-drive the element for the aboveobject.

One aspect of the invention is to drive the element by controlling afrequency for the above object.

One aspect of the invention is to provide an apparatus for, on drivingthe element, transitionally applying first voltage and switching tosecond voltage from that state for the above object.

One aspect of the invention is to provide an apparatus for, on using theelement as an optical system of a camera, inhibiting photography frombeing performed before a predetermined time passes from application ofvoltage to the element for the above object.

One aspect of the invention is to provide an apparatus for stoppingapplication of voltage when operation of an operating member forchanging a voltage signal to be applied to the element is not performedfor a predetermined time for the above object.

One aspect of the invention is to provide an apparatus for storing avoltage signal applied to the element at a last photography time andapplying a voltage signal corresponding to this stored value at a nextphotography time for the above object.

One aspect of the invention is to provide an apparatus for detectingelectrostatic capacity of an optical element to determine and control astate of interface form of an optical apparatus for the above object.

Other objects of the present invention will become clearer from theembodiments described hereunder by using the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are diagrams describing power supply controllingmethods of an optical element in the first embodiment of the presentinvention respectively;

FIG. 2 is a sectional view of an optical element in the first embodimentof the present invention;

FIG. 3 is a diagram describing operation on applying voltage to anoptical element in the first embodiment of the present invention;

FIGS. 4A and 4B are diagrams describing operation on applying DC voltageto an optical element of the present invention respectively;

FIGS. 5A and 5B are diagrams describing operation on applying AC voltageto an optical element of the present invention respectively;

FIG. 6 is a conceptual rendering of a driving frequency and a responsein an optical element of the present invention;

FIG. 7 is a diagram describing an optical element and power supply meansin the first embodiment of the present invention;

FIGS. 8A, 8B, 8C, 8D and 8E are diagrams describing operation of powersupply means in the first embodiment of the present invention;

FIG. 9 is a block diagram of an optical apparatus in the firstembodiment of the present invention;

FIG. 10 is a control flow diagram of an optical apparatus in the firstembodiment of the present invention;

FIGS. 11A, 11B and 11C are diagrams describing a power supplycontrolling method in the first embodiment of the present invention;

FIG. 12 is a block diagram of an optical apparatus in the secondembodiment of the present invention;

FIG. 13 is a control flow diagram of an optical apparatus in the secondembodiment of the present invention;

FIGS. 14A, 14B and 14C are diagrams describing power supply controllingmethods in the second embodiment of the present invention respectively;

FIGS. 15A, 15B and 15C are diagrams describing power supply controllingmethods in the second embodiment of the present invention respectively;

FIG. 16 is a sectional view of an optical element in the thirdembodiment of the present invention;

FIGS. 17A and 17B are diagrams describing operation on applying voltageto an optical element in the third embodiment of the present inventionrespectively;

FIG. 18 is a block diagram of an optical apparatus in the thirdembodiment of the present invention;

FIG. 19 is a control flow diagram of an optical apparatus in the thirdembodiment of the present invention;

FIGS. 20A, 20B, 20C and 20D are diagrams describing power supplycontrolling methods in the third embodiment of the present inventionrespectively;

FIGS. 21A, 21B, 21C and 21D are diagrams describing power supplycontrolling methods in the third embodiment of the present inventionrespectively;

FIG. 22 is a block diagram of an optical apparatus in the fourthembodiment of the present invention;

FIG. 23 is a main control flow diagram of an optical apparatus in thefourth embodiment of the present invention;

FIG. 24 is a sub-control flow diagram of an optical apparatus in thefourth embodiment of the present invention;

FIGS. 25A, 25B, 25C and 25D are diagrams describing relationship betweenapplied voltage and change of interface form of an optical element inthe fourth embodiment of the present invention respectively;

FIG. 26 is an example of temperature correction table in the fourthembodiment of the present invention;

FIG. 27 is a block diagram of an optical apparatus in the fifthembodiment of the present invention;

FIG. 28 is a main control flow diagram of an optical apparatus in thefifth embodiment of the present invention;

FIG. 29 is a sub-control flow diagram of an optical apparatus in thefifth embodiment of the present invention;

FIGS. 30A, 30B, 30C and 30D are diagrams describing relationshipsbetween applied voltage and change of interface form of an opticalelement in the fifth embodiment of the present invention, respectively;

FIG. 31 is a main control flow diagram of an optical apparatus in thesixth embodiment of the present invention;

FIG. 32 is a sub-control flow diagram of an optical apparatus in thesixth embodiment of the present invention;

FIGS. 33A and 33B are diagrams describing applied voltage control in thesixth embodiment of the present invention respectively;

FIG. 34 is a block diagram of an optical apparatus in the seventhembodiment of the present invention;

FIG. 35 is a main control flow diagram of an optical apparatus in theseventh embodiment of the present invention;

FIG. 36 is a sub-control flow diagram of an optical apparatus in theseventh embodiment of the present invention;

FIG. 37 is a block diagram of an optical element in the eighthembodiment of the present invention;

FIGS. 38A and 38B are diagrams describing operation on applying voltageto an optical element in the eighth embodiment of the present inventionrespectively;

FIG. 39 is a diagram describing optical action of an optical element inthe eighth embodiment of the present invention;

FIG. 40 is a block diagram of an optical apparatus in the eighthembodiment of the present invention;

FIG. 41 is a control flow diagram of an optical apparatus in the ninthembodiment of the present invention;

FIG. 42 is a block diagram of an optical apparatus in the tenthembodiment of the present invention;

FIG. 43 is a flowchart showing main control of an optical apparatus inthe tenth embodiment of the present invention;

FIG. 44 is a flowchart showing a subroutine of an optical apparatus inthe tenth embodiment of the present invention;

FIGS. 45A, 45B and 45C are detail drawings describing operation of anoptical element in the eleventh embodiment of the present inventionrespectively;

FIG. 46 is a diagram describing transmittance distribution of an opticalelement in the eleventh embodiment of the present invention;

FIG. 47 is a block diagram of an optical apparatus in the eleventhembodiment of the present invention;

FIG. 48 is a flowchart showing control of an optical apparatus in theeleventh embodiment of the present invention;

FIG. 49 is a block diagram of electrostatic capacity detecting means andpower supply means and a sectional view of an optical element in thetwelfth embodiment of the present invention;

FIG. 50 is a diagram of relationship between driving voltage anddetecting voltage in the twelfth embodiment of the present invention;

FIGS. 51A, 51B, 51C, 51D and 51E are diagrams describing voltagewaveform outputted from an amplifier of a power supply means related tothe twelfth embodiment of the present invention respectively;

FIG. 52 is a block diagram of an optical apparatus incorporating anoptical element related to the twelfth embodiment of the presentinvention;

FIG. 53 is a control flow diagram of an optical apparatus related to thetwelfth embodiment of the present invention;

FIG. 54 is a control flow diagram of an optical apparatus related to thetwelfth embodiment of the present invention;

FIG. 55 is a block diagram of an optical apparatus incorporatingelectrostatic capacity detecting means and power supply means and anoptical element related to the thirteenth embodiment of the presentinvention;

FIG. 56 is a control flow diagram of an optical apparatus related to thethirteenth embodiment of the present invention; and

FIG. 57 is a control flow diagram of an optical apparatus related to thethirteenth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIGS. 1A to 1C through FIGS. 11A to 11C are explanatory views fordescribing a configuration of a first embodiment of the presentinvention, and FIG. 2 is a sectional view showing a configuration of anoptical element of this embodiment. With reference to FIG. 2, at first,the configuration and a producing method of this embodiment will bedescribed.

In FIG. 2, reference numeral 101 denotes the optical element of thepresent invention in its entirety while reference numeral 102 denotes atransparent substrate made of transparent acryl in which a concaveportion is provided in the center thereof. On the upper face of thetransparent substrate 102, a transparent electrode (ITO) 103 made ofindium tin oxide is formed by sputtering, and in tight contact with theupper face thereof, an insulating layer 104 made of transparent acryl isprovided. The insulating layer 104 is formed by dripping replica resinonto the center of the above described transparent electrode 103, andpushing it with a glass plate for flattening and smoothing its surface,and thereafter radiation by UV is implemented for hardening and forming.Onto the upper surface of the insulating layer 104, a shadingcylindrical container 105 is fixed by gluing, and onto it a cover plate106 made of transparent acryl is fixed by gluing, and moreover onto it adiaphragm plate 107 having opening of diameter D3 in the center isdisposed. In the above described configuration, a sealed space of apredetermined volume enclosed by the insulating layer 104, the container105 and the upper cover 106, that is, a box having a liquid chamber isformed. In addition, surface treatment described below is implemented onthe wall of the liquid chamber.

At first, a water-repelling treatment agent is applied to the centralupper surface of the insulating layer 104 within the range of thediameter D1 to form a water-repelling film 111. For the water-repellingagent, fluoride compounds, etc. are suitable. In addition, in theoutskirt range beyond the diameter D1 on the upper surface of theinsulating layer 104, a hydrophilic treatment agent is applied so that ahydrophilic film 112 is formed. As a hydrophilic agent, surface-activeagent and hydrophilic polymer, etc. are suitable. On the other hand, onthe bottom surface of the cover plate 106, hydrophilic treatment isimplemented within a range of the diameter D2 so that a hydrophilic film113 having properties as the above described hydrophilic film 112 isformed. In addition, all the configuring members having been describedso far are shaped rotary symmetrical around an optical axis 123.Moreover, a hole is formed in a portion of the container 105, andthereto a stick-like electrode 125 is inserted and sealed by adhesiveagent to maintain a sealing state of the above-described liquid chamber.In addition, power supply means 126 is brought into connection with thetransparent electrode 103 and the stick-like electrode 125 and withoperation on a switch 127 a predetermined voltage is arranged to beapplicable between the both electrodes.

The liquid chamber configured as described so far will be filled withtwo kinds of liquid as described below. At first, onto thewater-repelling film 111 on the insulating layer 104 a predeterminedquantity of a second liquid 122 is dripped. The second liquid 122 iscolorless and transparent, and silicone oil which has specific gravityof 1.06 and a refractive index of 1.49 in a room temperature will beused. On the other hand, the remaining space inside the liquid chamberis filled with conductive or polarized first liquid 121. The firstliquid 121 is electrolytic solution, which is a mixture of water andethyl-alcohol at a predetermined ratio and moreover to which apredetermined quantity of salt (sodium chloride) is added, with specificgravity 1.06 and with refractive index 1.38 under a room temperature.That is, for the first and the second liquid, liquids which have thesame specific gravity and are insoluble each other are selected. There,the both liquids form an interface 124 and each of them existsindependently without being mixed together.

Next, the shape of the above-described interface will be described. Atfirst, in the case where no voltage is applied to the first liquid, theshape of the interface 124 is determined by interfacial tension betweenboth liquids, interfacial tension between the first liquid and thewater-repelling film 111 or the hydrophilic film 112 on the insulatinglayer 104, interfacial tension between the second liquid and thewater-repelling film 111 or the hydrophilic film 112 on the insulatinglayer 104, and volume of the second liquid. In this embodiment selectionof materials is implemented so that interfacial tension between siliconeoil being material for the second liquid 122 and the water-repellingfilm 111 becomes relatively small. That is, wet-aptness is high betweenboth materials and therefore the outer periphery of lens-shaped dropswhich the second liquid 122 form tends to expand and is stabilized wherethe outer periphery corresponds with the application region of thewater-repelling film 111. That is, the diameter A1 of the bottom surfaceof the lens which the second liquid forms is equal to the diameter D1 ofthe water-repelling film 111. On the other hand, since the specificgravity of the both liquids is the same as described above, gravity isnot influential. Then, the interface 124 becomes spherical, and theradius of curvature as well the height h1 thereof are determined by thevolume of the second liquid 122. In addition, thickness of the firstliquid on the optical axis will be t1.

On the other hand, when the switch 127 is operated to close so that avoltage is applied to the first liquid 121, electric capillaryphenomenon causes the interfacial tension between the first liquid 121and the hydrophilic film 112 to decrease and the first liquid trespassthe interface between the hydrophilic film 112 and the water-repellingfilm 111 to penetrate into region on the water-repelling film 111.Consequently, as in FIG. 3, the diameter of the bottom surface of thelens which the second liquid forms decreases from A1 to A2 while itsheight increases from h1 to h2. In addition, thickness of the firstliquid on the optical axis will be t2. Thus, application of voltage tothe first liquid 121 changes balance in the interfacial tensions of thetwo kinds of liquid so that the interface between the two liquids isdeformed. Accordingly, such an optical element that can freely deformthe interface 124 with voltage control on the power supply means 126 canbe realized. In addition, the first as well as the second liquid havedifferent refractive indexes to provide a power as an optical lens andtherefore the optical element 101 will be a variable focusing lens withdeformation of the interface 124.

Moreover, since compared with FIG. 2 the interface 124 in FIG. 3 isshorter in the radius of curvature, the optical element 101 in the stateshown in FIG. 3 has a focal length shorter than that in the state ashown in FIG. 2.

FIGS. 4A and 4B are explanatory views conceptually showing deformationprocess of the interface 124 of the optical element 101 when the powersupply means 126 are caused to give rise to a direct voltage.

In FIG. 4A, a step-like direct current voltage of voltage V₀ is appliedto the optical element 101 at time t₀. At this time, the interface whichboth liquids form in the optical element 101 responds as a curve shownin FIG. 4B. That is, the deformed amount starts with a predeterminedtime constant to reach a value of 95% of the final deformed amount δo attime t₁₂, and gets further closer toward δo, but regardless of thevoltage being applied, the subsequent deformed amount decreases. This isoriginated in that in FIG. 3 charges are gradually implanted into theinsulating layer 104 and electric capillary phenomenon is caused todecrease. In order to avoid this phenomena, it is described in page 158of Comptes Rendus des Seances dei'Academie des Science 317 (1993) thatan alternate current electric power supply of around 50 to 3 kHz can besuccessfully used as the power supply means 126.

Incidentally, the reference character δ conceptually denotes interfacedeformed amount, and does not mean a numerical value directly describingheight or contact angle of an interface but intensity of electriccapillary phenomenon.

FIGS. 5A and 5B are explanatory views conceptually showing deformationprocess of the interface 124 of the optical element 101 when the powersupply means 126 is caused to give rise to an alternate current voltage.

In FIG. 5A, when a sine-wave-like alternate current voltage of maximumvoltage V₀ with a predetermined frequency is applied to the opticalelement 101 at time t₀, the interface of the optical element 101responds as a curve shown in FIG. 5B. That is, the deformed amountstarts with a predetermined time constant to reach a value of 95% of thefinal deformed amount δsine at time t₁₂ as in FIG. 4B. And as timelapses, the deformed amount gets further closer toward δsine, butsubsequently never decreases.

As described so far, the optical element 101 has different responsecharacteristics at the time of interfacial deformation correspondingwith driving frequency of the power supply means. Under thecircumstances, the one in which deformed response of the interface 124of the optical element 101 to frequencies of voltages outputted from thepower supply means is conceptually shown is FIG. 6. In the presentdrawing, the horizontal axis represents frequencies of alternate currentvoltage supplied to the optical element 101 by the power supply meanswhile the vertical axis represents deformation velocity of the interfaceat the time of starting power supply, the interface deformed amount whensufficient time has lapsed from the start of power supply, and electricpower which the power supply means consumes.

According to the present drawing, the case of the driving frequency off₁, which gives rise to the phenomena shown in the above described FIG.4B and cannot provide a predetermined deformed amount, is inappropriateto control the optical state of the optical element 101 exactly. Thecase of the driving frequency of f₂ can provide a predetermined deformedamount but deformation (response) velocity is comparatively slow. Thecase of the driving frequency of f₃ can provide a predetermined deformedamount and deformation velocity is fast. The case of the drivingfrequency of f₄ can no longer provide a predetermined deformed amount.The reason hereof is that the optical element can be regarded as acapacitance having a predetermined electrostatic capacity, but sinceresistant of the transparent electrode 103 and ion mobility of theelectrolytic solution 122 are a limited values, the driving frequencybeing a high frequency will prevent electrical charge from beingimplanted into the optical element 101 so that the electric capillaryphenomenon will not take place effectively. That is, in order to controlthe optical element 101 effectively, it is necessary to appropriatelyset the electric power supply condition for driving this.

FIG. 7 and FIGS. 8A to 8E are explanatory views related to power supplymeans in the first embodiment of the present invention, and FIG. 7 is asectional view of the optical element of this embodiment and a drawingto show a configuration of power supply means.

In FIG. 7, reference numeral 130 denotes a central processing unit(hereinafter to be referred to as CPU) to control operation of alater-described optical apparatus 150 in its entirety, and is one-chipmicrocomputer having ROM, RAM, EEPROM, A/D converter function, D/Aconverter function, and PWM (Pulse Width Modulation) function. Referencenumeral 131 denotes power supply means for applying voltages to theoptical element 101, and its configuration will be described as follows.

Reference numeral 132 denotes a direct cuffent electric power supplyincorporated into the optical apparatus 150 such as a dry cell, etc.,reference numeral 133 denotes a DC/DC converter to increase the voltageoutputted from the electric power supply 132 to a desired voltage valuecorresponding with a control signal of the CPU 130, reference numerals134 and 135 are amplifiers to amplify in accordance with controllingsignals of the CPU 130, for example, frequency/duty ratio variablesignals to be realized by PWM (Pulse Width Modulation) function as thesignal levels to reach voltage levels increased with the DC/DCconverter. In addition, the amplifier 134 is brought into connectionwith the transparent electrode 103 of the optical element 101 and theamplifier 135 with a stick-like electrode 125 of the optical element 101respectively.

That is, corresponding with the controlling signals of the CPU 130,output voltage of the electric power supply 132 will be applied to theoptical element 101 by the DC/DC converter 133, the amplifier 134 andthe amplifier 135 with a desired voltage value, frequency and duty.

FIGS. 8A to 8E are explanatory views describing voltage waveforms to beoutputted from the amplifiers 134 and 135. Incidentally, underassumption that a voltage of 100V was outputted into the amplifiers 134and 135 from the DC/DC converter 133 respectively, following descriptionwill be implemented.

As having been shown in FIG. 8A, the amplifiers 134 and 135 arerespectively brought into connection with the optical elements 101. Fromthe amplifier 134, as shown in FIG. 8B, a voltage of rectangularwaveform with desired frequency and duty ratio is outputted by thecontrolling signals of the CPU 130. On the other hand, from theamplifier 135, as having been shown in FIG. 8C, a voltage of rectangularwaveform with the opposite phase of the amplifier 134, the samefrequency and the same duty ratio is outputted by the controllingsignals of the CPU 130. This will cause the voltage to be appliedbetween the transparent electrode 103 and the sticklike electrode 125 ofthe optical element 101 to become a rectangular waveform of ±100V, thatis, an alternate current voltage as shown in FIG. 8D.

Therefore, an alternate current voltage will be applied to the opticalelement 101 with the power supply means 131.

In addition, an effective voltage applied to the optical element fromthe application start of the voltage to be applied to the opticalelement 101 can be show as in FIG. 8E.

Incidentally, in the above described description, a rectangular waveformvoltage was described to be outputted from the amplifiers 134 and 135,but it goes without saying that a likewise configuration could beimplemented with sine waves.

In addition, in the above described description, the case where theelectric power supply 132 is incorporated into the optical apparatus 150was described, but the case where an exterior-type electric power supplyor power supply means implement alternate application into the opticalelement 101 will do as well.

FIG. 9 is the one in which the optical element 101 was applied to anoptical apparatus. In this embodiment, the optical apparatus 150 will beexemplified, for description, by so-called digital still camera whichconverts a still image into electric signals with photo-taking means andrecords them as digital data.

Reference numeral 140 denotes a photo-taking optical system comprising aplurality of lens groups and is configured with first lens group 141,second lens group 142, and the optical element 101. Forward and backwardmovement in the optical axis of the first lens group 141 implementsfocus adjustment. The optical element 101 undergoes power change toimplement zooming. Incidentally, in order to implement zooming in thephoto-taking optical system, normally power changes in a plurality oflens groups and movement of the groups is necessary, but for the presentdrawing, for the sake of simplicity the power changes in the opticalelement 101 are caused to represent the zooming operation. The secondlens group 142 is a relay lens group without movements. In addition, theoptical element 101 is disposed between the first lens group 141 and thesecond lens group 142, and a diaphragm unit 143 to adjust the lightamount of photo-taking optical flux by adjusting diaphragm aperture by aknown art is disposed between the first lens group 141 and the opticalelement 101.

In addition, the photo-taking means 144 is disposed in the focalposition (planned image forming surface) of the photo-taking opticalsystem 140. For this, photoelectric conversion means such as atwo-dimensional CCD, etc. comprising a plurality of photoelectricconversion portions to convert the irradiated optical energy intoelectrical charges, an electrical charge accumulating portion toaccumulate the electrical charges, and electrical charge transferportion to transfer the electrical charges and transmit them to outside.

Reference numeral 145 denotes an image signal process circuit, whichbrings the analog image signals inputted from the photo-taking means 144into A/D conversion, and implements image processing such as AGCcontrol, white balance, γ correction, and edge emphasis, etc.

Reference numeral 146 denotes a temperature sensor to measureenvironmental temperature (air temperature) in the optical apparatus150.

Reference numeral 147 is a look-up table provided in the memory regioninside the CPU 130, and there duty ratio data on the output voltage ofthe power supply means 131 necessary to control the optical power of theoptical element 101 at a predetermined value are stored in a mode of acorresponding table.

Reference numeral 151 denotes a display such as a liquid crystaldisplay, etc., and displays the subject image recognized by thephoto-taking means 144 and the operation status of the optical apparatushaving a variable focal lens. Reference numeral 152 denotes a mainswitch to drive the CPU 130 from the sleeping state to a state toexecute the program while reference numeral 153 denotes a zoom switch,and corresponding with switch operation by the photographer, the laterdescribed variable power operation is implemented so that the focallength of the photo-taking optical system 140 is changed. Referencenumeral 154 is operation switches other than the above describedswitches, which are configured by a pre-photo-taking switch,photo-taking commencement switch, and a photographic conditions setupswitch to set up shutter timing by second, etc.

Reference numeral 155 denotes focus detecting means and the focusdetecting means of phase difference detecting system, etc. used for asingle-lens reflex camera is suitable. Reference numeral 156 denotesfocusing operation means, which includes an actuator and a drivercircuit to move the first lens group 141 forward and backward in theoptical axis, implements focus operation based on the focus signalscalculated by the above described focus detecting means 155 so that thefocus state of the photo-taking optical system 140 is adjusted.Reference numeral 157 denotes memory means and the memory means recordsthe photographed image signals. In particular, a detachably attachablePC-card-type flush memory, etc. is suitable.

FIG. 10 is a control flow chart on the CPU 130 which the opticalapparatus 150 having been shown in FIG. 9 has. The control flow of theoptical apparatus 150 will be described with reference to FIG. 9 as wellas FIG. 10 as follows.

In the step S101, distinction on whether or not on-operation of the mainswitch 152 is executed is implemented and when the on-operation is notyet executed, a waiting mode state in which operation of variousswitches is waited for remains. In the step S101, when on-switchoperation of the main switch 152 is distinguished, the waiting mode willbe overridden and the process continues to the subsequent step S102 andonward.

In the step S102, the ambient temperature where the optical apparatus150 is disposed, that is, the periphery air temperature of the opticalapparatus 150 is measured with the temperature sensor 146.

In the step S103, setup of photographic conditions by a photographer isaccepted. For example, setup such as setup on exposure control mode(shutter priority AE and program AE, etc.), image quality mode (size inthe number of recording pixels and size of image compression rate,etc.), and the electronic flash mode (compulsory flash and flashprohibition, etc.), etc. is implemented.

In the step S104 distinction on whether or not the zoom switch 153 hasbeen operated by the photographer is implemented. In the case noon-operation has been executed, the process continues to the step S105.Here, in the case where the zoom switch 153 has been operated, theprocess continues to the step S121.

In the step S121, the operation quantity of the zoom switch 153(operation direction and on-time period, etc.) is detected. In the stepS122 the focal length control target value of the photo-taking opticalsystem 140 is calculated based on that operation quantity. In the stepS123 duty ratio on the voltage applied to the optical element 101corresponding to the above-described focal length control target valueis read out from the look-up table 147 in the CPU 130. The deformedamount of the optical element 101 directed to the duty ratio will bedescribed later with reference to FIGS. 1A to 1C and FIGS. 11A to 11C.In the step S124, power supply to the optical element 101 from the powersupply means 131 starts at the above-described duty ratio, and the statereturns to the step S103.

That is, while operation of the zoom switch 153 goes on, signals of apredetermined duty ratio corresponding with the operation quantity areapplied to the optical element 101 so that the process continues to thestep S105 at the time point when on-operation of the zoom switch 153 isover.

In the step S105 distinction on whether or not on-operation on thepre-photo-taking switch (indicated as SW1 in the flow chart in FIG. 10)among the operation switches 154 has been executed by the photographeris implemented. In the case where the on-operation is not executed, thestate returns to the step S103 so that acceptance for setup ofphotographic conditions and distinguishing on operation of zoom switch153 is repeated. Once the pre-photo-taking switch is determined to havebeen operated on in the step S105, the process continues on to the stepS111.

In the step S111, the photo-taking means 144 as well as the signalprocess circuit 145 is driven to acquire the preview image. The previewimage refers to an image to be acquired prior to photo-taking session inorder to appropriately set up the photo-taking conditions on the imagefor final recording as well as to make the photographer understand thephoto-taking construction.

In the step S112 the received light level of the preview image acquiredby the step S111 is recognized. In particular, in the image signalswhich the photo-taking means 144 output, the output signal levels ofmaximum, minimum and average are calculated so that the light amountemitted into the photo-taking means 144 is perceived.

In the step S113, based on received light amount recognized on theabove-described step S112, the diaphragm unit 143 provided within thephoto-taking optical system 140 is driven so that the aperture diameterof the diaphragm unit 143 is adjusted so as to be a proper light amount.

In the step S114, the preview image acquired in the step S111 isdisplayed in the display 151. Subsequently, in the step S115, with thefocus detecting means 155 the focus state of the photo-taking opticalsystem 140 is detected. Subsequently, in the step S116, with the focusdrive means 156, the first lens group 141 is caused to move forward andbackward toward the optical axis to implement accurate focusingoperation. Thereafter, the process continues to the step S117 todistinguish whether or not the on-operation of the photo-taking switch(which is expressed as SW2 in the flow chart FIG. 10) has beenimplemented. When it does not undergo on-operation, the state goes backto the step S111 and the steps covering from the acquisition of thepreview image to the focus drive is repeatedly executed. As describedabove, in the midst of executing the pre-photo-taking operationrepeatedly, the photographer could implement on-operation of thephoto-taking switch, and then the state leaps from the step S117 to thestep S131.

In the step S131, photo-taking session is implemented. That is, thesubject image formed on the photo-taking means 144 undergoesphotoelectric conversion, and the electrical charges in proportion tointensity of the optical image are accumulated in the electrical chargeaccumulating portion in the vicinity of each light receiving portion. Inthe step S132 the electrical charges accumulated in the step S131 isread out via accumulated electrical charge transfer line, and theread-out analog signals are inputted into the signal process circuit145. In the step S133, in the signal process circuit 145, the analogimage signals are inputted into A/D conversion, and image processingsuch as AGC control, white balance, γ correction, and edge emphasis,etc. are implemented, and moreover if there arises any necessity, JPEGcompression, etc. is implemented with image compression program storedinside the CPU 130. In the step S134 the image signals acquired in theabove-described step S133 are recorded into the memory 157. In the stepS135, at first the preview image displayed in the step S114 is erased,and the image signals acquired in the step S133 is again displayed onthe display 151. In the step S136 power supply output from the powersupply means 131 is stopped so that a series of photo-taking operationscome to an end in the step 137.

Next, actions in the step S123 in the above-described FIG. 10 will bedescribed with reference to FIGS. 1A to 1C and FIGS. 11A to 11C. FIGS.11A to 11C are explanatory views describing control method of the powersupply means and its effects in the case where the interface 124 of theoptical element 101 is deformed significantly and the focal length ofthe optical element 101 is made short.

FIG. 11A shows voltage waveform outputted from the power supply means131 and applied to the optical element 101, and its definition issimilar to the one having been described in FIG. 8D. This waveformrepresents an alternate current voltage of a rectangular wave with thepeak voltage of ±V₀ [v], frequency of 1 kHz, and duty ratio of 100%. Atthis time, the effective voltage applied to the optical element 101 willbe V₀ as in FIG. 11B and deformation of the interface 124 will get stillwith a predetermined deformation amount δ₁ as shown in FIG. 11C.

FIGS. 1A to 1C are explanatory views describing a control method of thepower supply means and its effects in the case where a deformationamount given to the interface 124 of the optical element 101 is smallerthan in FIG. 11.

FIG. 1A shows a voltage waveform outputted from the power supply means131 and applied to the optical element 101. This waveform represents analternate current voltage of a rectangular wave with the peak voltage of±V₀ [V] similar to that in FIG. 11, frequency of likewise 1 kHz, andduty ratio of 50%. At this time, the effective voltage applied to theoptical element 101 will be 0.5 V₀ as in FIG. 1B and deformation of theinterface 124 will get still with approximately half the deformationamount as shown in FIG. 11, that is, 0.5δ₁.

That is, in this embodiment, the peak voltage and the frequency of thedrive voltage outputted from the power supply means are always constant,and the duty ratio is made variable so that the effective voltage to besupplied to the optical element 101 is controlled and the deformationamount of the interface 124 is controlled. In addition, 1 kHz was takenfor this drive frequency in this embodiment, but this is equivalent tothe frequency in the vicinity of f₃ in FIG. 6. Selection of such afrequency enables the optical power of the optical element 101 to changerapidly and stably.

According to the above described first embodiment:

(1) The peak voltage and the frequency of the drive voltage outputtedfrom the power supply means are made to be constant, and only the dutyratio is made variable, which results in simple configuration of thepower supply means and can provide power supply means suitable todigital control with a microcomputer, etc. As a result thereof, opticalcharacteristics of an optical element will become accuratelycontrollable with an inexpensive control circuit; and,

(2) Since the output frequency of the power supply means has beenselected to be higher than the frequency with which electrical chargeimplantation into the insulating layer of the optical element takesplace and to be lower than the frequency with which electrical chargemovements due to increase in impedance are hampered, the interface canbe deformed on a stable basis, and the like will be attained.

Incidentally, in this embodiment, as an example of the optical element,a digital still camera which brings images into photoelectric conversionand records those data was taken, but it goes without saying that also avideo camera or a silver halide film camera recording images into asilver halide film, etc. can be taken likewise without spoiling theeffects.

Second Embodiment

The above-described first embodiment was a mode of an embodiment inwhich an alternate voltage with the peak voltage and the frequency beingconstant was applied to the optical element and duty of the alternatesignals is changed so that the interface of the optical element wasdeformed into a desired shape. In contrast hereto, as the secondembodiment, an embodiment in which an alternate cuffent voltage with thepeak voltage and duty being constant is applied to an optical element,and variation of frequency of that alternate signals deforms theinterface of the optical element into a desired shape will be shown.

FIG. 12 through FIGS. 15A to 15C are drawings to describe thisembodiment, and FIG. 12 is a drawing to show configuration of a opticalelement of this embodiment, or a drawing to show a digital still camera250 comprising the optical element 101 and the power supply means 131 asin the first embodiment.

A portion which differentiates the optical element 250 of thisembodiment from the optical element 150 of the first embodiment is apoint that the CPU 230 has a look-up table 247 which stores outputfrequency data of the power supply means 131 necessary for controllingthe optical power of the optical element 101 at a predetermined value ina mode of a corresponding table. Otherwise, the configuration andeffects are similar to those in the first embodiment and thereforedetailed description will be omitted.

FIG. 13 is a control flow chart on the CPU 230 which the opticalapparatus 250 in the second embodiment has. A portion whichdifferentiates the present flow chart from the flow chart in FIG. 10 inthe first embodiment is only the portion to readout data from the abovedescribed look-up table 247. This altered portion only will be describedas follows.

In the step S204 distinction on whether or not the zoom switch 153 hasbeen operated by the photographer is implemented, and in the case wherethe zoom switch 153 has been operated, the process continues to the stepS221.

In the step S221, the operation quantity of the zoom switch 153(operation direction and on-time period, etc.) is detected. In the stepS222 the focal length control target value of the photo-taking opticalsystem 140 is calculated based on that operation quantity. In the stepS223 frequency on the power supply signals applied to the opticalelement 101 corresponding to the above described focal length controltarget value are read out from the look-up table 127 in the CPU 230. Thedeformed amount of the optical element 101 directed to the frequencywill be described with reference to FIG. 14 and FIG. 15. In the stepS224, power supply to the optical element 101 from the power supplymeans 131 starts at the above described frequency, and the state returnsto the step S203.

Next, actions in the step S223 in the above described FIG. 13 will bedescribed with reference to FIGS. 14A to 14C and FIGS. 15A to 15C. FIGS.14A to 14C are explanatory views describing control method of the powersupply means and its effects in the case where the interface 124 of theoptical element 101 is deformed significantly and the focal length ofthe optical element 101 is made short.

FIG. 14A shows voltage waveform outputted from the power supply means131 and applied to the optical element 101, and its definition issimilar to the one having been described in FIG. 8D or FIG. 1A and FIG.11A. This waveform represents an alternate voltage of a rectangular wavewith the peak voltage of +V₀ [V], frequency of 2 kHz, and duty ratio of100%. At this time, the effective voltage applied to the optical element101 will be V₀ as in FIG. 11B and deformation of the interface 124 willget still with a predetermined deformation amount δ₂ as shown in FIG.11C.

FIGS. 15A to 15C are explanatory views describing control method of thepower supply means and its effects in the case where deformation amountgiven to the interface 124 of the optical element 101 is smaller than inFIGS. 14A to 14C.

The above described FIG. 15A shows a voltage waveform outputted from thepower supply means 131 and applied to the optical element 101. Thiswaveform represents an alternate voltage of a rectangular wave with thepeak voltage of ±V₀ [V] similar to that in FIGS. 14A to 14C, duty ratioof likewise 100%, and frequency of 4 kHz being a double. At this time,the effective voltage applied to the optical element 101 will be V₀ asin FIG. 14B and deformation of the interface 124 will as shown in FIG.15C get still with approximately half the deformation amount in FIGS.14A to 14C, that is, 0.5δ₂.

This is caused by this embodiments adoption of frequency in the vicinityof f₄ in FIG. 6. That is, this is caused since, with the power supplyvoltage having a frequency higher than a predetermined value, electricalcharges for deforming the interface 124 can no longer be supplied to theoptical element 101 easily, and occuaence of the electric capillaryphenomenon is controlled. Accordingly, since the deformation amount ofthe interface 124 decreases as the drive frequency increases, control onthe drive frequency can control the optical power of the optical element101 at a predetermined value.

According to the above described second embodiment:

(1) The peak voltage and the duty ratio of the drive voltage outputtedfrom the power supply means are made to be constant, and only thefrequency is made variable, which results in a simple configuration ofthe power supply means and can provide with control means suitable todigital control with a microcomputer, etc. As a result thereof, opticalcharacteristics of an optical element will become accuratelycontrollable with an inexpensive control circuit; and,

(2) Since the output frequency of the power supply means has beenselected to be a frequency higher than the frequency with whichelectrical charge movements into the optical element are hampered, theinterface can be deformed accurately and continuously by changes infrequency, and the like will be attained.

Incidentally, also in this embodiment, as an example of the opticalelement, a digital still camera was taken, but it goes without sayingthat also a video camera or a silver halide film camera, etc. other thanthat can be taken likewise without spoiling the effects.

Third Embodiment

FIG. 16 through FIGS. 21A to 21D are drawings to describe the thirdembodiment of the present invention, and FIG. 16 and FIGS. 17A and 17Bare drawings related to an optical element and power supply means to beused in this embodiment.

In FIG. 16, reference numeral 801 denotes the optical element in itsentirety, and reference numeral 802 denotes a disk-like transparentacryl or glass-made first sealing plate.

Reference numeral 803 denotes an electrode ring, and size of its outerdiameter is unanimous while the size of its inner diameter graduallychanges in the downward direction. That is, in this embodiment, it is ametal ring member the diameter of which gets gradually larger in thedownward direction on the size of inner diameter. An insulating layer804 made of acryl resin, etc. is formed in tight contact with the innerface of the whole periphery of the electrode ring 803. Since the innersize of the insulating layer 804 is unanimous, thickness graduallyincreases in the downward direction. In addition, to the bottom side ofthe inner face of the whole periphery of the insulating layer 804, awater-repelling treatment agent is applied so that a water-repellingfilm 811 is formed and to the upper side of the inner face of the wholeperiphery of the insulating layer 804, a hydrophilic treatment agent isapplied so that a hydrophilic film 812 is formed.

Reference numeral 806 is a disk-like transparent acryl-made orglass-made second sealing place, and a through-hole is opened in aportion thereof, and there a stick-like electrode 825 is inserted andsealed with an adhesive agent.

FIG. 16 is a sectional view to show configuration of an optical elementof this embodiment, and a drawing to show configuration of the powersupply means to drive this. With reference to FIG. 16, configuration ofthe optical element will be described.

Reference numeral 807 denotes a diaphragm plate to regulate the diameterof an optical flux to be emitted into the optical element 801, and isfixed-disposed on the upper surface of the second sealing plate 806. Inaddition, the first sealing plate 802, the metal ring 803 and the secondsealing plate 806 are fixed to each other by adhesive treatment, and abox having a sealed space in a predetermined volume enclosed by thesemembers, or a liquid chamber is formed. This box is shaped axiallysymmetric with respect to light axis 823 other than the portion wherethe above described stick-like electrode 825 is inserted. In addition,the liquid chamber is filled with two kinds of liquid described below.

At first, on the bottom side of the liquid chamber, the second liquid822 is dropped with only a quantity so that the height of its liquidpole reaches the same height as the forming portion of the abovedescribed water-repelling film 811. As the second liquid 822 siliconeoil which is colorless and transparent with specific gravity 1.06,refractive index of 1.38 is used. Subsequently, the remaining spaceinside the liquid chamber is filled with the first liquid 821. The firstliquid 821 is electrolytic solution, which is a mixture of water andethyl-alcohol at a predetermined ratio and moreover to which apredetermined quantity of salt (sodium chloride etc.) is added, withspecific gravity 1.06 and with refractive index 1.38 under a roomtemperature. Moreover, to the first liquid 821, uncolored water-solubledye, for example, carbon black or materials in the titan oxide systemare added. That is, for the first and the second liquid, liquids whichhave the same specific gravity and refractive index but have differentlight beam absorptive powers and are insoluble with each other areselected. There, both liquids form an interface 824 and each of themexists independently without being mixed together. In addition, theshape of this interface 824 is determined by the point where threesubstances of the inner wall of the liquid chamber, the first liquid andthe second liquid are brought into intersection, that is, the balance ofthree interfacial tensions applied to the outer periphery portion of theinterface 824. In this embodiment, the materials for the above-describedwater-repelling film 811 as well as hydrophilic film 812 are selected sothat the contact angle of the first and the second liquids toward theinner wall of the liquid chamber is 90 degrees respectively.

Since reference numeral 131 denotes a member having the sameconfiguration as well as function as in the power supply means describedin FIGS. 1A to 1C, detailed description will be omitted. The amplifier134 of the power supply means 131 is brought into connection with themetal ring 803 and the amplifier 135 with a stick-like electrode 825. Inthis configuration, voltages are applied to the first liquid 821 via thestick-like electrode 825 and the interface 824 is deformed byelectro-wetting effects.

Next, deformation of the above described interface 824 of the opticalelement 801 and the optical function given rise to by the deformationwill be described with reference to FIGS. 17A and 17B.

At first, in the case where no voltages are applied to the first liquid821, the shape of the interface 824 will be flat as described above(FIG. 17A).

Here, the second liquid is practically transparent, but the first liquidhas a predetermined light beam absorptive power due to an added lightabsorbing material. There, when a light flux is emitted in from theopening of the diaphragm plate 807, the light beam equivalent to thelight length of the first liquid is absorbed and the intensity of thelight flux emitted out from the second sealing plate 802 decreasesuniformly.

On the other hand, when voltages are applied to the first liquid, theshape of the interface 824 will become spherical due to electro-wettingeffects (FIG. 17B). There, on the light flux emitted in from the openingof the diaphragm plate 807, the absorption rate changes at a percentagecorresponding with changes in the light length in the first liquid, andthe intensity of the light flux emitted out from the second sealingplate 802 gradually decreases in the direction from the center towardthe periphery with its average intensity being higher than in the caseof FIG. 17A. That is, deformation of the interface 824 by the voltagecontrol of the power supply means 131 can realize an optical elementwhich can freely change the transmitting light amount.

In addition, since the refractive indexes for the first and the secondliquids are the same and only intensity of the emitted light can bechanged without changing the direction of the incident light flux, theelement can be used as diaphragm means to adjust the light amount of theincident light flux or an optical shutter to transmit or cut theincident light flux.

Incidentally, principles on the two-liquid interfacial deformation dueto electro-wetting is described in the above described internationalpatent WO99/18456, and the interface 824 in this embodiment isequivalent to the positions A and B of the two-liquid interfacedescribed in FIG. 6 of the above described patent. In addition,principles on the transmitting light amount adjustment of the incidentlight flux due to deformation of two-liquid interface and its effectsare described in Japanese Patent Application Laid-Open No. 11-169657made by the present applicant.

FIG. 18 is the one in which the optical element 801 was applied to anoptical apparatus. In this embodiment, as in the first embodiment, theoptical apparatus 150 will be exemplified, for description, by aso-called digital still camera which converts a still image intoelectric signals with photo-taking means and records them as digitaldata. Incidentally, as for those features similar to the ones in thefirst embodiment, detailed description thereon will be omitted.

In FIG. 18, reference numeral 430 denotes a photo-taking optical systemcomprising a plurality of lens groups and are configured by first lensgroup 431, second lens group 432, and the forth lens group 433. Forwardand backward movement in the optical axis of the first lens group 431implements focus adjustment. Forward and backward movement in theoptical axis of the second lens group 432 implements zooming. The fourthlens group 433 is a relay lens group without movement. In addition, anoptical element 801 is disposed between the second lens group 432 andthe fourth lens group 433. In addition, the photo-taking means 144 isdisposed in the focusing position (planned image forming surface) of thephoto-taking optical system 430.

Next, operation of the optical element 801 in this embodiment will bedescribed.

Dynamic range of luminance of subjects existing in the natural world isextremely large, and in order to limit this within a predeterminedrange, normally the interior of the photo-taking optical system has amechanical diaphragm mechanism to adjust light amount of thephoto-taking light flux. However, it is difficult to make the mechanicaldiaphragm mechanism small, and under a state of small diaphragm that thediaphragm opening is small, diffraction phenomena of the light beam dueto end surface of diaphragm wings occurs and, the resolution of thesubject image decreases. Thus, in this embodiment, the optical element801 is used as a variable ND filter replacing the above describedmechanical diaphragm mechanism so that without giving rise to the abovedescribed defects, the light amount passing through the photo-takingoptical system is adjusted appropriately.

FIG. 19 is a control flow chart on the CPU 330 which the opticalapparatus 350 having been shown in FIG. 18 has. The control flow of theoptical apparatus 350 will be described with reference to FIG. 18 aswell as FIG. 19 as follows. Incidentally, as for the control flowsimilar to that in the first embodiment, detailed description thereofwill be omitted.

In the step S301, distinction on whether or not on-operation of the mainswitch 152 is executed by the photographer is implemented and when theon-operation is not yet executed, the state remains in the step S301. Inthe step S301, when on-switch operation of the main switch 152 isdistinguished, the CPU 330 gets out of the sleep state so as to executethe step S302 and onward.

In the step S302, as in the first embodiment, the ambient temperaturewhere the optical apparatus 350 is disposed, that is, the periphery airtemperature of the optical apparatus 350 is measured with thetemperature sensor 146.

In the step S303, setup of photographic conditions by a photographer isaccepted. In the step S304, distinction on whether or not on-operationon the pre-photo-taking switch (indicated as SW1 in the flow chart) hasbeen executed by the photographer is implemented. In the case where theon-operation is not executed, the state returns to S303 so thatdistinguishing on acceptance for setup of photographic conditions isrepeated.

Once the pre-photo-taking switch is determined to have been operated onin the step S304, the process continues to the step S311.

Since steps S311 and S312 are similar to those in the first embodiment,description thereon will be omitted.

In the step S313, distinction on whether or not the received lightamount judged in the above described step S312 is appropriate isimplemented. In addition, when the present step recognizes itsappropriateness, the process continues to the step S314.

On the other hand, when in the step S313 it is distinguished that thereceived light amount judged in the above described step S312 is notappropriate, the state leaps to the step S321. In the step S321 theactual received light amount is compared with the appropriate receivedlight amount so as to calculate the appropriate transmittance to begiven to the optical element 801 inside the photo-taking optical system430. In the step S322 the voltage to be applied to the optical element801 is calculated in order to acquire the appropriate transmittancecalculated in the step S321. In particular, the ROM of the CPU 330stores the relationship on the transmittance toward the applied voltageas the form of look-up table 347, the applied voltage V₃ directed to thetransmittance calculated in the step S321 is acquired with reference tothe table. That is, in order to control the interfacial deformationamount of the optical element, the duty ratio of the alternate outputfrom the power supply means in the first embodiment and the frequency inthe second embodiment were switched, but in the third embodiment, thepeak voltage is switched.

In the step S323, the power supply means applies to the optical element801 an alternate cuffent voltage with the peak voltage of ±V₃ and thefirst frequency. Here, in this embodiment, the first frequency is set at1 kHz. Then, the interface 824 of the optical element 801 is deformedinto a predetermined shape corresponding with the effective value of theinput voltage, and the light flux transmittance of the element 801 iscontrolled at the desired value.

After execution of the step S323, the state returns to the step S311,and until the incident light amount into the photo-taking means 144becomes appropriate, the steps from image signals acquisition in thestep S311 to the step 323 are executed repeatedly. In addition, when theincident light amount into the photo-taking means 144 becomesappropriate, the state shifts from the step S313 to the step S314.

In the step S314, the frequency of the alternate signals outputted fromthe power supply means 131 is switched with the second frequency. Inthis embodiment, the second frequency is set at 250 Hz, but effects dueto this switching will be described with reference to FIG. 20 and FIG.21 later.

In the step S315, the preview image acquired in the step S311 isdisplayed in the display 151. Subsequently, in the step S316, with thefocus detecting means 155 the focus state of the photo-taking opticalsystem 430 is detected. Subsequently, in the step S317, with the focusdrive means 156, the first lens group 431 is caused to move forward andbackward toward the optical axis to implement accurate focusingoperation. Thereafter, the process continues to the step S318 todistinguish whether or not the on-operation of the photo-taking switch(which is expressed as SW2 in the flow chart FIG. 19) has beenimplemented. When it does not undergo on-operation, the state goes backto the step S311 and the steps covering from the acquisition of thepreview image to the focus drive is repeatedly executed.

As described above, if in the midst of executing the pre-photo-takingoperation repeatedly, the photographer implements on-operation of thephoto-taking switch, then the state leaps from the step S318 to the stepS331. In the step S331, the frequency of the alternate signals outputtedform the power supply means 131 is switched with the first frequency.That is, the frequency is made to get back to 1 kHz from 250 Hz.

In the step S332, photo-taking session is implemented. That is, thesubject image having been formed on the photo-taking means 144 undergoesphotoelectric conversion, and the electrical charges in proportion tointensity of the optical image are accumulated in the electrical chargeaccumulating portion in the vicinity of each light receiving portion. Inthe step S333, the electrical charges accumulated in the step S131 areread out via accumulated electrical charge transfer line, and theread-out analog signals are inputted into the signal process circuit145. In the step S334, in the signal process circuit 145, the analogimage signals are inputted into A/D conversion, and image processingsuch as AGC control, white balance, γ correction, and edge emphasis,etc. are executed, and moreover if there arises any necessity, JPEGcompression, etc. is implemented with image compression program storedinside the CPU 330. In the step S335 the image signals acquired in theabove described step S334 are recorded into the memory 157. In the stepS336, at first the preview image displayed in the step S315 is erased,and the image signals acquired in the step S334 is again displayed onthe display 151. In the step S337, power supply outputs from the powersupply means 131 is stopped so that a series of photo-taking operationscome to an end in the step 338.

Next, influence and effects in switching of the frequency of the powersupply means output will be described with reference to FIGS. 20A to 20Dand FIGS. 21A to 21D. FIG. 20 is explanatory views describing controlmethod of the power supply means and its effects in the case where theoutput of the power supply means 131 is with the first frequency, thatis, 1 kHz.

FIG. 20A shows voltage waveform outputted from the power supply means131 and applied to the optical element 101, and its definition issimilar to the one having been described in FIG. 8D. This waveformrepresents an alternate current voltage of a rectangular wave with thepeak voltage of ±V₃ [V], frequency of 1 kHz, and duty ratio of 100%. Thefrequency 1 kHz here is equivalent to f₃ in FIG. 6. At this time, theeffective voltage applied to the optical element 101 will be V₃ as inFIG. 20B, and the electric power consumption in the power supply means131 will be shown in FIG. 20C. That is, since the optical element 801 isstructured as a capacitor, after application of a constant voltage,in-flow current decreases as electrical charges are accumulated, andtherefore, the electric power consumption repeats minute variations insynchronization with switching on polarity of the voltage of theelectric power supply as shown in FIG. 20C. The peak value of theelectric power consumption at this time is assumed to be W30 and theaverage value to be W31 respectively. In addition, the interface 824 isdeformed with waveform shown in FIG. 20D.

FIGS. 21A to 21D are explanatory views describing control method of thepower supply means and its effects in the case where the output of thepower supply means 131 is with the second frequency, that is, 250 kHz,and respective waveforms constitute the same meaning as in FIGS. 20A to20D.

FIG. 21A shows voltage waveform outputted from the power supply means131 and applied to the optical element 101, and is an alternate currentvoltage of a rectangular wave with the peak voltage of ±V₃ [V] the sameas in FIGS. 20A to 20D, and duty ratio of 100% also the same as in FIGS.20A to 20D while the frequency is 250 Hz. The frequency 250 Hz here isequivalent to f₂ in FIG. 6. At this time, the effective voltage appliedto the optical element 101 will be V₃ as in FIG. 21B, and the electricpower consumption in the power supply means 131 will be shown in FIG.21C. That is, since the frequency of the signals of power supply to theoptical element 801 has decreased, the electric power consumption variesmore significantly than that having been shown in FIG. 20C. Accordingly,the electric power consumption average value W₃₂ is lower than in thecase of FIGS. 20A to 20D. In addition, the interface 824 is deformedwith waveform shown in FIG. 21D, but the interfacial deformationvelocity at this time is slower than in the case of FIG. 20D. However,after the interfacial deformation amount becomes still with apredetermined value δ3, the interfacial shape gets stable.

According to descriptions so far, with alternate signals with highfrequencies to be applied to the optical element 801, the electric powerconsumption gets larger but the response velocity of the interface getsfaster while with the signals with low frequencies the response getsslower but the electric power consumption may be less. Accordingly, inthis embodiment, as having been shown in the step S323 in FIG. 19, inthe case where the interface shape of the optical element is deformed,application of high frequency makes swift deformation possible. On theother hand, as having been shown in the step S314 in FIG. 19, in thecase where deformation comes to an end and a predetermined shape ismaintained, the drive frequency is switched to a low frequency so as toattain power saving. In this case, deformation of the interface 824 isalready over, and therefore slowness in response velocity of theinterface will not become any obstacle.

In addition, in this embodiment, as having been shown in the step S331in FIG. 19, immediately prior to photo-taking operation, the drivefrequency is caused to get back to a high frequency. This serves tostrengthen the interface constraint power of the optical element at thetime of a photo-taking session, and reduce variation in opticalcharacteristics due to external disturbances during a photo-takingsession. In addition, since photo-taking time period is short, increasein electric power consumption will not become any serious obstacles.

According to the above-described third embodiment:

(1) The frequency of the drive signals outputted from the power supplymeans are switched appropriately corresponding with the state of theoptical apparatus so that without sacrificing the deformation velocityof the optical element energy saving on the power supply means can beplanned; and

(2) At the time when high stability is required in the optical element ahigh frequency drive signal is supplied and at the time when lowstability is tolerable a low frequency drive signal is supplied so thatwithout reducing performance of the optical apparatus energy saving onthe power supply means can be planned, and the like will be attained.

Incidentally, in this embodiment, as an example of the optical element,a digital still camera was taken, but it goes without saying that also avideo camera or a silver halide film camera, etc. other than that can betaken likewise without spoiling the effects. In addition, the powersupply control method of the optical element 801 of this embodiment maybe applied to the first embodiment and the second embodiment to attainsimilar effects, and the power supply control method of the firstembodiment and the second embodiment may be applied to the thirdembodiment to attain similar effects.

Fourth Embodiment

FIG. 22 shows another example in which the optical element 101 shown inFIG. 2 has been applied to an optical apparatus. In this embodiment, thesame symbols are given for the same configuration as in theconfiguration having been shown in FIG. 9. A timer 147′ provided in theCPU 130 is provided to this embodiment, and time set by the CPU 130 iscounted.

FIG. 23 is a control flow chart of the CPU 130 which the opticalapparatus 150 having been shown in FIG. 22 has. The control flow of theoptical apparatus 150 will be described with reference to FIG. 22 aswell as FIG. 23 as follows.

In the step S1101, distinction on whether or not on-operation of themain switch 152 is executed is implemented and when the on-operation isnot yet executed, a waiting mode state in which operation of variousswitches is waited for remains. In the step S1101, when on-switchoperation of the main switch 152 is distinguished, the waiting mode willbe overridden and thereafter the process continues to the subsequentstep S1102.

In the step S1102, the ambient temperature where the optical apparatus150 is disposed, that is, the periphery air temperature of the opticalapparatus 150 is measured with the temperature sensor 146.

In the step S1103 setup of photographic conditions by a photographer isaccepted. For example, setup such as setup on exposure control mode(shutter priority AE and program AE, etc.), image quality mode (size inthe number of recording pixels and size of image compression rate,etc.), and the electronic flash mode (compulsory flash and flashprohibition, etc.), etc. is implemented.

In the step S1104 distinction on whether or not the zoom switch 153 hasbeen operated by the photographer is implemented. In the case noon-operation has been executed, the process continues to the step S1105.Here, in the case where the zoom switch 153 has been operated, theprocess continues to the step S1121.

In the step S1121 distinction on whether or not the timer 147′ is in themidst of counting is implemented. If counting is not going on, theprocess continues to the step S1123, and in the case where counting isgoing on, after resetting the counter value (S1122), the state continuesto the step S1123.

In the step S1123, the operation quantity of the zoom switch 153(operation direction and on-time period, etc.) is detected, and thecorresponding varied amount of focal length is calculated based on thatoperate amount (S1124). As the result of that calculation, the referencevoltage value to be applied finally V₀ to the optical element 101 isdetermined (S1125), and the process continues to the subroutine of“temperature correction” to correct standard voltage value to be appliedfinally in terms of temperature and decide the waveform of applyingvoltage (the details will be described later). The power supply means131 are controlled with the corrected finally applying voltage value andapplying waveform pattern to be applied to the optical element 101decided in the subroutine so that a voltage is applied to the opticalelement (S1127). Concurrently therewith, counting of the timer 147′ isstarted (S1128). And the state goes back to the step S1103. That is, inthe case where operation of the zoom switch 153 goes on, the step S1103to the step S1128 are repeatedly executed so that the process continuesto the step S1105 at the time point when on-operation of the zoom switch153 is over.

In the step S1105 distinction on whether or not on-operation on thepre-photo-taking switch (indicated as SW1 in the flow chart in FIG. 23)among the operation switches 154 has been executed by the photographeris implemented. In the case where the on-operation is not executed, thestate returns to the step S1103 so that acceptance for setup ofphotographic conditions and distinguishing on operation of zoom switch153 are repeated. Once the pre-photo-taking switch is determined to havebeen operated on in the step S1105, the process continues to the stepS1111.

In the step S1111, the photo-taking means 144 as well as the signalprocess circuit 145 is driven to acquire the preview image. The previewimage refers to an image to be acquired prior to photo-taking session inorder to appropriately set up the photo-taking conditions on the imagefor final recording as well as to make the photographer understand thephoto-taking construction.

In the step S1112 the received light level of the preview image acquiredby the step S1111 is recognized. In particular, in the image signalswhich the photo-taking means 144 output, the output signal levels ofmaximum, minimum and average are calculated so that the light amountemitted into the photo-taking means 144 is precieved.

In the step S1113, based on the received light amount recognized by theabove described step S1112, the aperture stop unit 143 provided in thephoto-taking optical system 140 is driven so that the aperture diameterof the aperture stop unit 143 is adjusted so as to obtain a proper lightamount.

In the step S1114, the preview image acquired in the step S1111 isdisplayed in the display 151. Subsequently, in the step S1115, with thefocus detecting means 155 the focus state of the photo-taking opticalsystem 140 is detected. Subsequently, in the step S1116, with the focusdrive means 156, the first lens group 141 is caused to move forward andbackward toward the optical axis to implement accurate focusingoperation. Thereafter, the process continues to the step S1117 todistinguish whether or not the on-operation of the photo-taking switch(which is expressed as SW2 in the flow chart FIG. 23) has beenimplemented. When it does not undergo on-operation, the state goes backto the step S1111 and the steps covering from the acquisition of thepreview image to the focus drive is repeatedly executed.

As described above, if in the midst of executing the pre-photo-takingoperation repeatedly, when the photographer implements on-operation ofthe photo-taking switch, whether or not counting of the timer 147′ iscompleted is distinguished (S1118). In the case where counting is notyet completed, distinction will go on as is, and at the time point whencounting of the timer 147′ is completed, the state leaps from the stepS1118 to the step S1131, and after the counted value of the timer 147′is reset (S1131), the process continues to the step S1132.

In the step S1132, photo-taking session is implemented. That is, thesubject image having been formed on the photo-taking means 144 undergoesphotoelectric conversion, and the electrical charges in proportion tointensity of the optical image are accumulated in the electrical chargeaccumulating portion in the vicinity of each light receiving portion. Inthe step S1133 the electrical charges accumulated in the step S132 areread out via accumulated electrical charge transfer line, and theread-out analog signals are inputted into the signal process circuit145. In the step S1134, in the signal process circuit 145, the analogimage signals are inputted into A/D conversion, and image processingsuch as AGC control, white balance, γ correction, and edge emphasis,etc. are implemented, and moreover if there arises any necessity, JPEGcompression, etc. is implemented with image compression program storedinside the CPU 130. In the step S1135, the image signals acquired in theabove described step S1134 are recorded into the memory 157, and at thesame time, in the step S1136 the preview image is erased once, andafterwards the image signals acquired in the step S1134 is againdisplayed on the display 151. Thereafter, the power supply means 131 iscontrolled to stop voltage application to the optical element 101(S1137) so that a series of photo-taking operations come to an end.

Next, the case where temperature correction is implemented will bedescribed with reference to FIG. 24 and FIGS. 25A to 25D. In the stepS1151, distinction on whether or not the air temperature measured withthe temperature sensor 146 is not less than 15° C. is implemented. Inthe case where the air temperature is not more than 15° C., the waveformof applying voltage A having been shown in FIG. 25A is selected (S1152).At the time of low temperature, viscosity of the liquids 121 and 122 inthe optical element 101 becomes high to lengthen the time period untilthe interface completes deformation, and therefore by applying voltagehigher than a predetermined final voltage reference value V₀ at thestartup after the electric power supply is switched on, the interfacialdeformation amount at the time of startup is made to increase so thatthe completion time period of the interfacial deformation is planned tobe short.

In this waveform pattern, for a predetermined time period prior to thefirst voltage to be applied to the optical element 101, that is, thefinal voltage reference value V₀ is applied (hereinafter to be referredto as pre-applying time), the second voltage higher than the finalvoltage reference value V₀, that is, the prevoltage value V₁ is appliedto the optical element 101, and after the pre-applying time lapses thefinal voltage reference value V₀ is applied to the optical element 101.

In the case where the measured air temperature is not less than 10° C.and less than 15° C. (S1153), the pre-applying time is set at 0 ms(S1154), and the process continues to the S1180 where the prevoltagevalue V₁ is calculated.

In the case where the measured air temperature is not less than 5° C.and less than 10° C. (S1155), the pre-applying time is set at 10 ms(S1156), and the process continues to the S1180 where the prevoltagevalue V₁ is calculated.

In the case where the measured air temperature is not less than 0° C.and less than 5° C. (S1160), the pre-applying time is set at 20 ms(S1156), and the process continues to the S1180 where the prevoltagevalue V₁ is calculated.

In the case where the measured air temperature is less than 0° C.(S1160), the pre-applying time is set at 30 ms (S1156), and the processcontinues to the S1180 where the prevoltage value V₁ is calculated.

The prevoltage value V₁ calculated in the step S1180 is given by forexample an equation as follows:Prevoltage value V ₁=(correction constant 1)×(referencetemperature−measured temperature)  Equation (1-1)

That is, the value obtained by multiplying (correction constant 1) tothe temperature difference against the reference temperature, that is,15° C. will be the prevoltage value V₁. After the prevoltage value V₁ isgiven, the process continues to the step S1181 so that correction amountof the final voltage reference value V₀ is calculated and the finalvoltage applying time is given. The final voltage reference value V₀ isalready given in the step S1125, but is also corrected using correctionexpressed, for example, by the following equation.

$\begin{matrix}{{{Corrected}\mspace{14mu}{final}\mspace{14mu}{voltage}\mspace{14mu}{value}\mspace{14mu} V_{0}^{\prime}} = {\left( {{final}\mspace{14mu}{voltage}\mspace{14mu}{reference}\mspace{14mu}{value}\mspace{14mu} V_{0}} \right) + {\left( {{correction}\mspace{14mu}{constant}\mspace{14mu} 2} \right) \times \begin{pmatrix}{{{reference}\mspace{14mu}{temperature}} -} \\{{measured}\mspace{14mu}{temperature}}\end{pmatrix}}}} & {{Equation}\mspace{14mu}\left( {1\text{-}2} \right)}\end{matrix}$

That is, the final voltage reference value V₀ given in the step S1125 isadded to the value obtained by multiplying (correction constant 2) tothe temperature difference against the reference temperature, that is,15° C., resulting in the corrected final voltage value V₀′.

Controlling as described so far is implemented so that the applyingvoltage waveform is delicately altered as having been shown in FIG. 25Acorresponding with temperature, and consequently the interface responsewaveform will approximately constant regardless of temperatures as inFIG. 25C, and deformation is completed at the time point t₃₂. Under thecircumstances, the waiting time period of the timer 147′ to be regardedas the reference of completion of deformation is made T_(A) slightlylonger than t₃₂, and T_(A) is stored in the memory of the CPU 1130 inadvance. In addition, in the step S1118 in FIG. 23 this T_(A) is treatedas a judgment value of timer completion so that execution of flow of andafter the step S1131 is permitted after the interface gets still.

On the other hand, in the case where in the step S151 the measuredtemperature is not less than 15° C., the waveform of applying voltage Bhaving been shown in FIG. 25B is selected (S1170). In this relation, atthe time of high temperature, viscosity of the liquids 121 and 122 inthe optical element 101 becomes low to result in occurrence ofoscillating phenomena before the interface completes deformationsometimes, and therefore by applying voltage gradually increasing toreach a predetermined final voltage reference value V₀ at the startupafter the electric power supply is switched on, the interfaceoscillation phenomena at the time of startup is planned to besuppressed.

In this waveform pattern, for a predetermined time period before thefinal voltage reference value V₀ to be applied to the optical element101 is applied (also hereinafter to be referred to as pre-applyingtime), the voltage control is implemented so as to gradually reach thefinal voltage reference value V₀.

In the case where the measured air temperature is not less than 15° C.and less than 20° C. (S1171), the pre-applying time is set at 10 ms(S1172), and the process continues to the S1181 where the correctedfinally applying voltage value V₀′ is calculated and time period of thefinally applying voltage is calculated.

In the case where the measured air temperature is not less than 20° C.and less than 30° C. (S1173), the pre-applying time is set at 20 ms(S1174), and the process continues to the S1181 where the correctedfinally applying voltage value V₀′ is calculated and time period of thefinally applying voltage is calculated.

In the case where the measured air temperature is not less than 30° C.(S1173), the pre-applying time is set at 30 ms (S1175), and the processcontinues to the S1181 where the corrected finally applying voltagevalue V₀′ is calculated and time period of the finally applying voltageis calculated.

Controlling as described so far is implemented so that the applyingvoltage waveform is delicately altered as having been shown in FIG. 25Bcorresponding with temperature, and consequently the interface responsewaveform will be approximately constant regardless of temperatures as inFIG. 25D, and deformation is completed at the time point t₄₂. Under thecircumstances, the waiting time period of the timer 147′ to be regardedas the reference of completion of deformation is made T_(B) slightlylonger than t₄₂, and T_(B) is stored in the memory of the CPU 130 inadvance. In addition, in the step S1118 in FIG. 23 this T_(B) is treatedas a judgment value of timer completion so that execution of flow of andafter the step S1131 is permitted after the interface gets still.

As described so far, the finally applying voltage value and the waveformpattern of applying voltage corresponding to temperatures are decided(S1182), and thus the state is returned to the step 1127.

In addition, it is possible to implement optimum drive control forrespective temperatures by controlling the finally applying voltagevalue and the waveform pattern of applying voltage depending ontemperature.

According to the above described fourth embodiment:

(1) The finally applying voltage value and the waveform pattern ofapplying voltage to the optical element are controlled correspondingwith temperatures so that an optical apparatus that can shorten the timeperiod of deformation completion of the optical element can be madeavailable;

(2) Since the time period to drive the optical element could beshortened actually, electric power consumption can be reduced; and,

(3) Since exposure is prohibited until the deformation of the opticalelement gets still, such a case that the photo-taking operation of theoptical apparatus is influenced is annulled, and the like will beattained.

Incidentally, in this embodiment, the reference temperature forswitching the waveform pattern of the applying voltage is set at 15° C.and the pre-applying time is set for respective temperatures, similareffects can be attained by setting the reference temperature as well asthe pre-applying time by configuration of the optical element and thekinds and combination of liquids thereof, etc.

In addition, the voltage was applied to the optical element in twostages, but with a multi-stage arrangement involving more stages similareffects can be attained.

Moreover, the corrected amount of the finally applying voltage value aswell as the pre-applying voltage value for respective temperatures weregiven by calculation, but effects similar to those in this embodimentcan be attained as well by storing, as having been shown in FIG. 26, forexample, a table decided by the temperature of the desired focal lengthand using it as respective correction amounts.

Incidentally, in this embodiment, as an example of the optical element,a digital still camera was taken, but it goes without saying that also avideo camera or a silver salt camera, etc. other than that can be takenlikewise without spoiling the effects.

Fifth Embodiment

The above described fourth embodiment was an embodiment in the casewhere voltages are applied to the optical element without anything beingapplied thereto. On the contrary hereto, the fifth embodiment to beshown as follows is a configuration example in which in the case where avoltage is applied to the optical element and interface thereof is stillan operation to alter its interface shape was executed.

FIG. 27 and FIG. 30 are drawings related to the fifth embodiment of thepresent invention.

FIG. 27 is the one in which a digital still camera as an example of theoptical element 101 as in the fourth embodiment was applied to theoptical apparatus. As for those similar to the ones in the fourthembodiment, description thereon will be omitted.

In the above described drawing, the optical apparatus 150 has a W sidezooming switch 201 for making respective optical systems such asphoto-taking optical systems and observation optical systems such as afinder, etc. and the like zoom to the wide-angle side and a T sidezooming switch 202 for making the above-described optical systems zoomto the telephotographic side.

FIG. 28 and FIG. 29 are a control flow chart of the optical apparatus150 having been shown in FIG. 27. The control flow of the opticalapparatus 150 will be described with reference to FIG. 28 as well asFIG. 29 as follows.

Since the state from the step S1201 to the step S1203 up to acceptancefor setup of photographic conditions is similar to those in the fourthembodiment, descriptions thereon will be omitted.

In the step S1204, distinction on whether or not the photographer hasoperated the W side zoom switch 201 is implemented. In the case noon-operation has been executed, the process continues to the step S1205.Here, in the case where the W side zoom switch 201 has been operated,the process continues to the step S1221.

In the step S1205, distinction on whether or not the T side zoom switch202 has been operated by the photographer is implemented. In the case noon-operation has been executed, the process continues to the step S1206.Here, in the case where the T side zoom switch 202 has been operated,the process continues to the step S1221.

In the step S1206, distinction on, as in the fourth embodiment, whetheror not on-operation on the pre-photo-taking switch (indicated as SW1 inthe flow chart in FIG. 28) among the operation switches 154 has beenexecuted by the photographer is implemented. In the case where theon-operation is not executed, the state returns to the step S1203 sothat acceptance for setup of photographic conditions and distinguishingon operation of respective zoom switches is repeated. Once thepre-photo-taking switch is determined to have been operated on in thestep S1206, the process continues to the step S1211.

Since the control flow from the step S1211 to the step S1237 is similarto those in the fourth embodiment, descriptions thereon will be omitted.

In the step S1221, to which the process continues in the case where theW side zoom switch 201 or the T side zoom switch 202 was operated in thestep S1204 or in the step S1205, distinction on whether or not the timer147′ is in the midst of counting is implemented. In the case wherecounting is not going on, the process continues to the step S1222 and asin the fourth embodiment a series of control flow from “detection ofoperated amount of zoom switch” in the step S1222 to “timer start” inthe step S1227 is implemented, and therefore description thereon will beomitted.

On the other hand, in the case wherein the step S1221 it isdistinguished that the timer 147′ is counting, that is, a predeterminedamount of voltage is applied to the optical element 101, the processcontinues to the subroutine of “finally applied voltage correction” inthe step S1228.

Next, correction on finally applied voltage will be described withreference to FIG. 29 and FIG. 30.

In the step S1251, the counter value of the timer 147′ is reset. Next,in the step S1252, the operation quantity of the zoom switch which hasbeen operated is detected, and the corresponding varied amount of focallength is calculated based on that operate amount (S1253).

In the step S1254, which zoom switch has been operated is distinguished.In the case where the W side zoom switch 201 has been operated, theprocess continues to the step S1255, and in the case where the T sidezoom switch 202 has been operated, the process continues to the stepS1257.

The result that the W side zoom switch 201 has been operated in thedistinction in the step S1254 means that the voltage value applied tooptical element 101 is caused to increase to further deform theinterface 124 so that the focal length of the optical element 101 isshortened, and therefore in the step S1255, the direction in whichfinally applied voltage value is corrected as in the direction indicatedin FIG. 30A. In addition, from the voltage value V_(A) applied to theoptical element 101, value V₂ which is obtained by adding the correctionvalue to the finally applying voltage reference value V₀ to be given bythe varied amount of focal length is decided as the corrected finallyapplied voltage value in the case where the W side zooming switch 201has been operated, and therefore, V₀ as well as its correction amount iscalculated in the step S1256.

Incidentally, the correction amount at this time may be decided bycalculation, or may be a table value in the memory in the CPU 130decided corresponding to the finally applied voltage reference value V₀.Thus, as shown in FIG. 30C, with V₀ being the finally applied voltagevalue, the interface 124 of the optical element 101 changes as shown ina broken line in accordance with lapse of time, and deformation takesplace only to an optically unacceptable deformation amount, for example,0.90δ_(A) with respect of the desired deformation amount δ_(A) at thefinal stage, but with V₂ being the finally applied voltage value, theinterface 124 changes as shown in a bold line in accordance with lapseof time, and deformation reaches finally the desired amount δ_(A). Thatis, the desired focal length changes of the optical element 101 willhave been given.

On the other hand, the result that the T side zoom switch 202 has beenoperated in the distinction in the step S1254 means that the voltagevalue applied to optical element 101 is caused to decrease deformationamount of the interface 124 of the optical element 101 so that the focallength of the optical element 101 is lengthened, and therefore in thestep S1257, the direction in which finally applied voltage value iscorrected as in the direction indicated in FIG. 30B. In addition, fromthe voltage value V_(B) applied to the optical element 101, value V₃which is obtained by adding the correction value to the finally applyingvoltage reference value V₀ to be given by the varied amount of focallength is decided as the corrected finally applied voltage value in thecase where the T side zooming switch 201 has been operated, andtherefore, V₀ as well as its correction amount is calculated in the stepS1258.

Incidentally, the correction amount at this time may be decided bycalculation, or may be a table value in the memory in the CPU 130decided corresponding to the finally applied voltage reference value V₀.

Thus, as shown in FIG. 30D, with V₀ being the finally applied voltagevalue, the interface 124 of the optical element 101 changes as shown ina broken line in accordance with lapse of time, and deformation takesplace only to an optically unacceptable deformation amount, for example,0.90δ_(B) with respect to the desired deformation amount δ_(B) at thefinal stage, but with V₃ being the finally applied voltage value, theinterface 124 changes as shown in a bold line in accordance with lapseof time, and deformation reaches finally the desired amount δ_(B).

That is, the desired focal length changes of the optical element 101will have been given.

When calculation of the finally applied voltage value as well as itscorrection amount is completed in the step S1256 and in the step S1258,the process continues to the “temperature correction” subroutine in thestep S1225.

At this time, with V₂ or V₃ being the finally applied voltage value, thetemperature correction toward the finally applied voltage valuedescribed in the fourth embodiment is implemented, but detaileddescription thereof will be omitted.

As having been described so far, when, in the case where the opticalelement 101 is still in the midst of voltage application, an operationto alter its interface shape was executed, since the correction amountsand the correction directions are respectively set for the case in whichalteration takes place from the wide-angle side and for the case inwhich alteration takes place from the telephotographic side even if thefinally applied voltage value directed to the desired focal length isV₀, the finally applied voltage value will differ. Thus, even in thecase where hysteresis has taken place in deformation of the interface124 with respect to the voltage shift to be applied to the opticalelement 101, setup of appropriate correction amount as well as thecorrection direction can cancel its influence.

According to the above described fifth embodiment:

(1) Since the finally applied voltage value is respectively decidedaccording to applied voltage shifted direction to the optical element,changes in optical characteristics of the optical element becomepossible without being influenced by hysteresis; and,

(2) since the optical element can be controlled canceling influence ofhysteresis, correct operation reflecting intention of the photographerbecomes possible, and the like will be attained.

Sixth Embodiment

FIG. 31 and FIG. 32 are flow charts related to a sixth embodiment of thepresent invention. Incidentally, the optical apparatus of thisembodiment shall be similar to the fifth embodiment.

FIG. 31 and FIG. 32 are control flow charts on the optical apparatus ofthis embodiment. The control flow on the optical apparatus will bedescribed with reference to FIG. 31 and FIG. 32 as follows.

As for the common control flow between FIG. 28 being the control flowchart of the fifth embodiment and FIG. 31 being the control flow chartof this embodiment, descriptions thereon will be omitted. Here, thevoltage application control method to the optical element 101 aftertemperature correction was implemented in the step S1325 (referenceshould be made to the following description on “control of voltage to beapplied” of the step S1326) is different.

Under circumstances, in order to clear this issue, control of voltage tobe applied will be described with reference to FIG. 32 and FIG. 33.

In the step S1351, distinction on whether or not the zoom switchoperated by the photographer is the W side zoom switch 201 isimplemented. In the case where the W side zoom switch 201 has beenoperated, the process continues to the step S1352, and in the case wherethe T side zoom switch 202 has been operated, the state goes forward tothe step S1361.

In the step S1352, the first applying voltage value V₄ for the correctedfinally applied voltage value V₀′ given in the step S1325 is calculatedand its applying time t₇₀ is set. This first applying voltage value V₄is given by for example the following equation:First applying voltage value V ₄=(corrected finally applied voltagevalue V ₀′)−(constant)  Equation (3-1)

“Constant” and application time in this equation (3-1) may be thoseeither read out from a memory stored in the CPU 130 or given by anequation performed on the correction finally applied voltage value V₀′.

Thus, after the first applying voltage value V₄ and its applying timet₇₀ are given, in the step S1353 applying the first applying voltagevalue V₄ is started, and concurrently therewith the timer 147′ startscounting (S1354). After counting for the applying time set in the stepS1352 is completed (S1355), counting of the timer 147′ is completed andapplication of corrected finally applied voltage value V₀′ being thesecond applying voltage starts (S1356 and S1357). And the state returnsto the step S1327.

In the step S1361, the third applying voltage value V₅ for the correctedfinally applied voltage value V₀′ given in the step S1325 is calculatedand its applying time t₈₀ is set. This third applying voltage value V₅is given by for example the following equation:Third applying voltage value V ₅=(corrected finally applied voltagevalue V ₀′)−(constant)  Equation (3-2)

“Constant” and application time t₈₀ in this equation (3-2) may be thoseeither read out from a memory stored inside the CPU 130 or given by anequation performed on the correction finally applied voltage value V₀′.

Thus, after the third applying voltage value V₅ and its applying timet₈₀ are given, in the step S1362 applying the third applying voltagevalue V₅ is started, and concurrently therewith the timer 147′ startscounting (S1363). After counting for the applying time set in the stepS1361 is completed (S1364), counting of the timer 147 is completed andapplication of corrected finally applied voltage value V₀′ being thefourth applying voltage starts (S1365 and S1366). And the state returnsto the step S1327.

As having been described so far, regardless of the direction of changesin focal length of the optical element 101, application of voltage lowerthan the corrected finally applied voltage value V₀′ for a predeterminedtime before the corrected finally applied voltage value V₀′ is appliedto the optical element 101 will make the direction to which theinterface 124 of the optical element 101 is made stable be the directionto which the radius of curvature of the interface 124 is made small.That is, even in the case where hysteresis has taken place indeformation of the optical element 101, with voltage applying directiontoward the optical element 101 at the time when the interface 124 ismade stable being constant, consideration on only one direction of theinfluence of hysteresis will become necessary and its correction willbecome easy.

Incidentally, in the above-described description, voltage applyingdirection toward the optical element 101 at the time when the interfaceis made stable should be the voltage value increasing direction, butwithout being limited hereto, adoption of the voltage value increasingdirection can direct the influence of hysteresis to a direction so thatsimilar effects can be attained.

Accordingly, to the above-described sixth embodiment, voltageapplication is made in a constant direction when the interface of theoptical element is made stable so that it will become possible toimplement correction on the portion influenced by hysteresis of theoptical element easily.

Seventh Embodiment

The above-described fourth embodiment and sixth embodiment were modes ofembodiment in the case where the optical element was incorporated intothe photo-taking optical system of the optical apparatus. In contrast,the seventh embodiment described as follows is an example ofconfiguration in the case where the optical element was incorporatedinto the optical system other than the above described one.

FIG. 34 through FIG. 36 are drawings related to the seventh embodimentof the present invention.

FIG. 34 is the one when the optical element 101 was incorporated intothe observatory optical system 330 of the optical apparatus. As forthose similar to the ones in the fourth embodiment and the fifthembodiment, description thereon will be omitted.

In the above-described drawing, the optical apparatus 150 has aneyesight adjustment switch 159. This eyesight adjustment switch 159 maybe either a lever-type one or push-button-type one, and with operationthereof, the CPU 130 controls the power supply means to alter theapplying voltage to the optical element 101. That is, operation of theeyesight adjustment switch 159 changes focal length of the opticalelement 101 so that the focus of the observed image can be matched withthe diopter of the photographer.

Reference numeral 330 denotes a observatory optical system comprising aplurality of lens groups and are configured by first lens group 331,second lens group 332, third lens group 333, vision frame 334 disposedin the approximate focal position of this optical system, and theoptical element 101. Forward and backward movement in the optical axisof the second lens group 332 implements zooming. In addition, the thirdlens group 333 is a relay lens group without movements. Thereby, theobserver can observe the observatory image formed in the focal positionthrough the optical element 101.

FIG. 35 and FIG. 36 are control flow charts on the CPU 130 which theoptical apparatus 150 having been shown in FIG. 34 has. The control flowof the optical apparatus 150 will be described with reference to FIG. 35through FIG. 36 as follows.

In the step S1401, distinction on whether or not on-operation of themain switch 152 is executed is implemented and when the on-operation isnot yet executed, a waiting mode state in which operation of variousswitches is waited for remains. On the other hand, in the step S1401,when on-switch operation of the main switch 152 is distinguished, thewaiting mode is overridden and the process continues to the subsequentstep S1402.

In the step S1402, the corrected finally applied voltage value V₀′ ofthe optical element 101 stored in the CPU 130 is confirmed.Incidentally, in the case where the optical apparatus 150 is used forthe first time, the corrected finally applied voltage value V₀′=0V isset in the CPU 130.

In the step S1403, based on the result of the above-described stepS1402, in the case where there is a set value in the CPU 130, theprocess continues to the subroutine of “memory set” while in the casewhere there is no memory value the process continues to the step S1404.In the case where there is a set value in the CPU 130, that set value isread out again (S1451), based on that set value the corrected finallyapplied voltage value V₀′ to the optical element 101 is set (S1452), andthereafter the power supply means 144 is controlled to apply the voltageto the optical element 101, and the state goes back to the originalstate (S1453).

In the step S1404, setup of photographic conditions by a photographer isaccepted. For example, setup such as setup on exposure control mode(shutter priority AE and program AE, etc.), image quality mode (size inthe number of recording pixels and size of image compression rate,etc.), and the electronic flash mode (compulsory flash and flashprohibition, etc.), etc. is implemented.

In the step S1405, distinction on whether or not the eyesight adjustmentswitch 159 has been operated by the photographer is implemented. In thecase no on-operation has been executed, the process continues to thestep S1406. Here, in the case where the eyesight adjustment switch 159has been operated, the process continues to the step S1421.

In the step S1421, the operation quantity of the eyesight adjustmentswitch 159 (operation direction and on-time period, etc.) is detected,and the corresponding eyesight adjustment amount is calculated based onthat operate amount (S1422). As per that calculation outcome, thefinally applied voltage value V₀ to the optical element 101 isdetermined (S1423), “temperature correction” described in the fourthembodiment is implemented (S1424), and thereafter the output voltage ofthe power supply means 131 is controlled so that the corrected finallyapplied voltage value V₀′ is applied to the optical element 101 (S1425).And the state goes back to the step S1404. That is, in the case whereoperation of the eyesight adjustment switch 159 goes on, the step S1404to the step S1425 are repeatedly executed so that the process continuesto the step S1406 at the time point when on-operation of the eyesightadjustment switch 159 is over.

In the step S1406, distinction on whether or not on-operation on thepre-photo-taking switch (indicated as SW1 in the flow chart in FIG. 35)among the operation switches 154 has been executed by the photographeris implemented. In the case where the on-operation is not executed, thestate returns to the step S1404 so that acceptance for setup ofphotographic conditions and distinguishing on operation of eyesightadjustment switch 159 is repeated. In addition, once thepre-photo-taking switch is determined to have been operated on in thestep S1406, the process continues to the step S1411.

Since the step S1411 to the step S1417 are similar to the step S1111 tothe step S1117 in the fourth embodiment, and the step S1431 to the stepS1435 are similar to the step S1132 to the step S1136 in the fourthembodiment, descriptions thereon will be omitted.

After the photographed image in the step S1435 is displayed in thedisplay 151, in the step S1436 distinction on whether or not theoff-operation of the main switch 152 is implemented. In the case wherethe off-operation is not yet implemented on the main switch 152, theprocess continues to the step 1404, and a series of photo-takingoperations from S1404 to S1435 are repeatedly implemented.

In addition, in the case the off-operation was implemented on the mainswitch 152 in the step S1436, the process continues to the step S1437 torewrite the corrected finally applied voltage value V₀′ to the opticalelement 101 stored in the CPU 130 to the corrected finally appliedvoltage value V₀′ immediately prior to the off-operation of the mainswitch 152, and thereafter the process continues to the step S1438 tostop voltage application to the optical element 101 so that a series ofphoto-taking operations come to an end.

As described so far, also when the optical element was incorporated inthe observatory optical system, it will become possible to control thefinally applied voltage value and the waveform pattern of applyingvoltage to the optical element corresponding with temperature. That is,the optical element may be incorporated into any optical system so thatsimilar effects can be attained.

Eighth Embodiment

FIG. 37 through FIG. 40 are drawings related to the eighth embodiment ofthe present invention. Since configurations in FIGS. 37, 38 and 39 arethe same as those in FIGS. 16, 17 and 18, descriptions will be omitted.

FIG. 40 is a control flow chart on the CPU 130 which the opticalapparatus 150 having been shown in FIG. 39 has. The control flow of theoptical apparatus 150 will be described with reference to FIG. 39 andFIG. 40 as follows. Incidentally, as for the control flow similar tothat in the fourth embodiment, detailed descriptions thereon will beomitted.

In the step S1501, distinction on whether or not on-operation of themain switch 152 is executed by the photographer is implemented and whenthe on-operation is not yet executed, the state remains in the stepS1501. In the step S1501, when on-switch operation of the main switch152 is distinguished, the CPU 130 gets out of the sleep state so as toexecute the step S1502 and onward.

In the step S1502, as in the fourth embodiment, the ambient temperaturewhere the optical apparatus 150 is disposed, that is, the periphery airtemperature of the optical apparatus 150 is measured with thetemperature sensor 146.

In the step S1503, setup of photographic conditions by a photographer isaccepted.

In the step S1504, distinction on whether or not on-operation on thepre-photo-taking switch (indicated as SW1 in the flow chart) has beenexecuted by the photographer is implemented. In the case where theon-operation is not executed, the state returns to S1503 so thatdistinguishing on acceptance for setup of photographic conditions isrepeated.

Once the pre-photo-taking switch is determined to have been operated onin the step S1504, the process continues to the step S1511.

Since the step S1511 as well as the step S1512 are similar to those inthe fourth embodiment, description thereon will be omitted.

In the step S1513, distinction on whether or not the received lightamount judged in the above-described step S1512 is appropriate isimplemented. In addition, when in the present step its appropriatenessis recognized, the process continues to the step S1514.

On the other hand, when in the step S1513 it is distinguished that thereceived light amount judged in the above described step S1512 is notappropriate, the state leaps to the step S1521. Since the step S1521 aswell as the step S1522 are similar to those in the fourth embodiment,description thereon will be omitted. In the step S1523, the actualreceived light amount is compared with the appropriate received lightamount so as to calculate the appropriate transmittance of the opticalelement 801 in the photo-taking optical system 430. In the step S1524the control voltage (finally applied voltage value V₀) is calculated inorder to acquire the appropriate transmittance calculated in theabove-described step S1523. In particular, the ROM of the CPU 130 storesthe relationship on the transmittance toward the applied voltage in theform of look-up table, the finally applied voltage value V₀ with respectto the transmittance calculated in the step S1523 is acquired withreference to the table.

In the step S1525, temperature correction with respect to the finallyapplied voltage value V₀ is implemented as in the fourth embodimentwhile in the step S1526 the power supply means 131 are controlled withthe finally applying voltage reference value and applying waveformpattern to be applied to the optical element 801 decided in thesubroutine of the above-described “temperature correction” so that avoltage is applied to the optical element 801. Concurrently therewith,counting of the timer 147 is started (S1527). After the step S1527 isexecuted, the state goes back to the step S1511, and the steps fromacquisition of the image signals of the step S1511 to the step S1527 arerepeated until the incident light amount into the photo-taking means 144becomes appropriate. And when the incident light amount into thephoto-taking means 144 become appropriate, the process continues fromthe step S1513 to the step S1514.

Since the step S1514 to the step S1537 are similar to those in thefourth and the fifth embodiments, description thereon will be omitted.

Ninth Embodiment

FIG. 41 shows another control flow chart when the above-describedoptical element 101 (shown in FIG. 2) was applied to the opticalapparatus 150 (in FIG. 9). Since this flow has the step 2123 decidingthe applying voltage although the step 123 decides the duty ratio inFIG. 10, representing only difference, descriptions on other points willbe omitted.

Tenth Embodiment

The above-described ninth embodiment was a mode of embodiment in whichimmediately after completion of photo-taking operation power supply tothe optical element is switched off. Here, the case where thephotographer can set the time for putting off power supply to theoptical element will be described as the tenth embodiment of the presentinvention as follows with reference to FIG. 42 to FIG. 44.

FIG. 42 is the one in which the optical element 101 was applied to anoptical apparatus equivalent to a digital still camera as in the ninthembodiment. As for those similar to the ones in the above-describedninth embodiment, description thereon will be omitted.

In FIG. 42, the CPU 142 has a timer 146 in its interior. The timer 146is for counting set time as described later. The optical apparatus 141has a menu switch 158. This menu switch 158 is to implement respectivesettings such as brightness adjustment of the display 151 and setting onphoto-taking date and time, etc. and has among those setting items anitem to set the time for power supply to the optical element 101 aftercompletion of photography. In addition, as for those setting items, atleast two kinds of setting, for example, the setting to put off powersupply immediately after completion of photography and the setting toput off power supply in ten seconds after completion of photographyshall be feasible.

FIG. 43 and FIG. 44 are control flow charts on the CPU 142 which theoptical apparatus 141 having been shown in FIG. 42 has, which will bedescribed with reference to FIG. 42 to FIG. 44 as follows.

At first, in the step S2201, distinction on whether or not on-operationof the main switch 152 is executed is implemented and when theon-operation is not yet executed, the state enters a waiting mode statein which operation of various switches is waited for. Thereafter, whenon-switch operation of the main switch 152 is distinguished, the waitingmode is overridden and the process continues to the step S2202. Inaddition, in this step S2202 set values of the timer 146 stored in theCPU 142 is confirmed. Incidentally, in the case where the opticalapparatus 141 is used for the first time, a certain set value (forexample counted value=0) is stored in the CPU 142.

In the next step S2203, setup of photographic conditions by aphotographer is accepted. For example, setup such as setup on exposurecontrol mode (shutter priority AE and program AE, etc.), image qualitymode (size in the number of recording pixels and size of imagecompression rate, etc.), and the electronic flash mode (compulsory flashand flash prohibition, etc.), etc. is implemented. In addition, in thenext step S2204 it is judged whether or not the menu switch 158 has beenoperated by the photographer, and in the case no on-operation has beenexecuted, the process continues to the step S2205. In addition in thecase where the menu switch 158 has been operated, the process continuesto the subroutine of the step S2210. This sub-routine will be describedwith reference to FIG. 44 as follows.

In the step S2251, in FIG. 44 it is judged to which the count value ofthe timer 146 is set by the menu switch 158, and in the next step S2252that setup value is replaced with the setup value stored in the CPU 142,and thereafter the process continues to the step S2205 in FIG. 43.

Incidentally, operation of the menu switch 158 implements brightnessadjustment of the display 151 and setting on photo-taking date and time,etc., but since the flow is similar to the above-described one,description thereon will be omitted here.

Back to FIG. 43, in the step S2205 it is judged whether or not the zoomswitch 153 was operated by the photographer, and in the case noon-operation has been implemented, the process continues to the stepS2206. In addition, in the case where the zoom switch 153 is operated,the process continues to the step S2221.

Since operations from the step S2221 to the step S2224 are similar tothe above described ones, descriptions thereon will be omitted.

In the next step S2224, a voltage is applied to the optical element 101,and thereafter, in the next step S2225, in the case where the timer 146has started counting, that count value is reset, and in the subsequentstep S2226 the timer 146 is made to start counting again so that thestate goes back to the step S2203.

That is, in the case where operation of the zoom switch 153 goes on, thestep S2205 to the step S2226 are repeatedly executed so that the processcontinues to the step S2206 at the time point when on-operation of thezoom switch 153 is over. That is, while the zoom operation is going on,the timer is not practically caused to start counting.

In the step S2206, it is judged whether or not on-operation on thepre-photo-taking switch among the operation switches 154 has beenexecuted by the photographer. In the case no on-operation has beenexecuted, the process continues to the step S2207 and when the timer 146has started counting it is judged here whether or not the value countingis completed, or the state returns to the step S2203 in the case wherethe counting is not completed so that acceptance for setup ofphotographic conditions and judgment on operation of the menu switch 158and the zoom switch 153 are repeated. On the other hand, in the casewhere value counting of the timer 146 is completed in the step S2207,the process continues to the step S2208, and after the counted value ofthe timer 146 is reset, the process continues to the step S2237 (theflow thereafter will be described later).

In addition, in the case where in the above-described step S2206 it isjudged that on-operation on the pre-photo-taking switch has beenexecuted, the process continues to the step S2211.

In the case where the on-operation of the photo-taking switch isexecuted in the step S2217, since the step S2211 to the step S2234 aresimilar to those in the above-described ninth embodiment, descriptionsthereon will be omitted.

When the process continues to the next step S2235, the photographedimage is displayed in the display 151 here, and in the next step S2236it is judged whether or not the counting value of the timer 146 is set.In the case where the counting value of the timer 146 is not set, theprocess continues to the step S2237 to control the power supply means144 and to switch off the voltage application to the optical element 101so that a series of photo-taking operation comes to an end.

In addition, in the case where in the above-described step S2236 acounting value of the timer 146 is set, the state returns to the stepS2203 again.

Hereafter, in the case where various kinds of switches are not operatedduring counting, until that counting value is completed, each step ofstep sequence of S2203 to S2204 to S2205 to S2206 to S2207 to S2203 isrepeated, but when the counting is completed, the process continues fromthe step S2207 to the step S2208, the counting value of theabove-described timer 146 is reset, and the process continues to thestep S2237 to switch off the voltage application to the optical element101 so that a series of photo-taking operation comes to an end.Incidentally, when on-operation on the photo-taking switch is notexecuted in the above-described step S2217, the process continues to thestep S2207. Since configuration is made like this, voltage applicationto the optical element 101 is suspended automatically when photographyis not implemented for a set time after zoom operation is executed. Inaddition, when photo-taking operation is executed within the set time,and photography is completed, but the set time has not yet lapsed,suspension of voltage application is executed after the set time haslapsed thereafter.

According to the above described tenth embodiment, effects as describedbelow will be attained:

1) Regardless of the photo-taking operation, in the case where operationon various operation switch group is not executed, the voltageapplication to the optical element 101 can be switched off, andtherefore power saving of the optical apparatus in its entirety willbecome feasible.

2) Since the photographer himself/herself can set the voltage applyingtime to the optical element 101, power saving operation reflecting thephoto-taking situation and the photographer's intention, etc. willbecome possible.

Eleventh Embodiment

The tenth embodiment was a mode of embodiment in the case where theoptical element was applied to focal length alterations of variousoptical systems of the optical apparatus. Here, the case of applicationas an optical filter previously applied by the present applicant will bedescribed as the eleventh embodiment of the embodiments in the presentinvention with reference to FIGS. 45A to 45C through FIG. 48.

FIGS. 45A to 45C are sectional views to describe configuration of theoptical element 201 related to the eleventh embodiment of the presentinvention and drawings to describe operations in the case of using it asan optical filter. The optical element is configured similar to the oneshown in the above described FIG. 2, that is, reference numeral 202corresponds with the transparent substrate 102, reference numeral 203does with transparent electrode (ITO) 103, reference numeral 204 doeswith the insulating layer 104, reference numeral 205 does with thecontainer 105, reference numeral 206 does with the cover plate 106,reference numeral 207 does with the diaphragm plate 107, referencenumeral 211 does with the water-repelling film 111, reference numeral212 does with the hydrophilic film 112, reference numeral 213 does withthe hydrophilic film 113, reference numeral 223 does with the opticalaxis 123, reference numeral 225 does with the stick-like electrode 125,and reference numeral 226 does with the power supply means 126respectively.

The points and the configuration of the optical element 201 that aredifference from the optical element 101 are as follows.

The liquid chamber of the optical element 201 will be filled with twokinds of liquids as described below. At first, onto the water-repellingfilm 211 on the insulating layer 204 a predetermined quantity of asecond liquid 222 is dripped. The second liquid 222 is colorless andtransparent, and silicone oil which has specific gravity of 0.85 and arefractive index of 1.38 in a room temperature will be used. On theother hand, the remaining space inside the liquid chamber is filled withthe first liquid 221. This first liquid 221 is electrolytic solution,which is a mixture of water and ethyl-alcohol at a predetermined ratioand moreover to which a predetermined quantity of sodium chloride isadded, with specific gravity 0.85 and with refractive index 1.38 under aroom temperature. Moreover, to the first liquid 221, uncoloredwater-soluble dye, for example, carbon black or materials in the titanoxide system are added. That is, for the first and the second liquid,liquids which have the same specific gravity and refractive index buthave different light beam absorptive powers and are insoluble with eachother are selected. There, the both liquids form an interface 224 andeach of them exists independently without being mixed together.

Next, the shape of the above described interface will be described.

At first, in the case where no voltage is applied to the first liquid,the shape of the interface 224 is determined by interfacial tensionbetween the both liquids, interfacial tension between the first liquidand the water-repelling film 211 or the hydrophilic film 212 on theinsulating layer 204, interfacial tension between the second liquid andthe water-repelling film 211 or the hydrophilic film 212 on theinsulating layer 204, and volume of the second liquid. In this mode ofembodiment selection of materials is implemented so that interfacialtension between silicone oil being material for the second liquid 222and the water-repelling film 211 becomes relatively small. That is,wet-aptness is high between the both materials and therefore the outerperiphery of lens-shaped drops which the second liquid 222 form tends toexpand and is stabilized where the outer periphery corresponds with theapplication region of the water-repelling film 211. That is, thediameter A1 of the bottom surface of the lens which the second liquid222 forms is equal to the diameter D1 of the water-repelling film 111.On the other hand, since the specific gravity of the both liquids is thesame as described above, gravity are not influential. Then the interface224 becomes spherical, and the radius of curvature as well as the heighth1 thereof are determined by the volume of the second liquid 222. Inaddition, thickness of the first liquid on the optical axis will be t1.

Here, the second liquid 222 is practically transparent, but the firstliquid 221 has a predetermined light beam absorptive power due to anadded light absorbing material. There, when a light flux is emitted infrom the opening of the diaphragm plate 207, the light beam equivalentto the light length of the first liquid 221 is absorbed and theintensity of the light flux emitted out from the transparent substrate202 decreases. That is, since reducing rate in the light intensity is inproportion to thickness on the optical axis of the first liquid 221 (t1in FIG. 11), deformation of the interface 224 by the voltage control ofthe power supply means 226 can realize an optical element which canfreely change the transmitting light amount. In addition, the refractiveindexes for the first and the second liquids are made to be the same andonly intensity of the emitted light can be changed without changing thedirection of the incident light flux.

FIGS. 45A to 45C are drawings to describe, in further detail, operationsin the case where the optical element 201 is used as a variable NDfilter.

FIG. 45A shows the case where the output voltage of the power supplymeans 226 brought into connection with the optical element 201 is zeroor extremely low V1.

As for the shape of the interface 224 at this time, the bottom surfaceof the lens forming the second liquid 222 has a diameter being A1 and aheight being h1. In addition, thickness on the optical axis of the firstliquid 221 is t1. L_(IN) is a light flux irradiated from above theoptical element 201 and emitted into the opening of the diaphragm 207,and L_(OUT) is a light flux emitted from the optical element 201. Inaddition, the ratio L_(OUT) against the light flux L_(IN) will be thetransmittance of the optical element 201, but since the thickness t1 onthe optical axis of the first liquid 221 is large, the transmittancewill become low. In addition, as for the light amount distribution ofthe emitted light flux L_(OUT), larger the distance from the opticalaxis, that is, the incident height is, the light amount will bedecreased, but since the opening diameter D3 of the diaphragm 207 ismade small against the diameter A1 of the bottom surface of the lenswhich the liquid 222 forms, the light amount distribution of the emittedlight flux L_(OUT) can be regarded as approximately unanimous.

FIG. 45B shows the case of the output voltage of the power supply means226 being V2 larger than V1.

At this time, the diameter of the bottom surface of the lens which thesecond liquid 222 forms is A2, and the height thereof is h2. Inaddition, thickness of the first liquid 221 on the optical axis is t2smaller than t1 in FIG. 45A. There, the transmittance of the light fluxwill become larger than in the case of FIG. 45A.

FIG. 45C shows the case of the output voltage of the power supply means226 being V3 larger than V2.

At this time, the diameter of the bottom surface of the lens which thesecond liquid 222 forms will shrink to A3, and the top of the interface224 will be brought into contact with the hydrophilic film 213 formed onthe lower surface of the cover plate 206 to become flat. In addition,the diameter of this flat portion is equal to the diameter D3 of theopening of the diaphragm 207 or larger than D3. Consequently, thethickness on the optical axis of the first liquid 221 becomes zero, asthe transmittance will become further larger than in the case of FIG.45B. Thereafter, even if the output voltage of the power supply means226 is made to increase further, the interface 224 inside the opening ofthe diaphragm 207 is not deformed, and therefore, the transmittance inthe case where the optical element was used as a variable ND filter willremain constant. The transmittance at this time is expressed bymultiplication of transmittances of the transparent substrate 202, thetransparent electrode 203, the insulating layer 204, water-repellingfilm 211, the second liquid 222, the hydrophilic film 213, and the coverplate 206.d

Incidentally, when the applying voltage of the power supply means 226 isreturned from the state in FIG. 45C to V1, the interface tension of bothliquids will go back to the original state. At this time, wet-aptness isgood between the first liquid 221 and the hydrophilic film 213 whilewet-aptness is poor between the second liquid 222 and the hydrophilicfilm 213, and therefore the second liquid 222 leaves the hydrophilicfilm 213 to come back to the state in FIG. 45A. That is, deformation ofthe interface 224 of the present optical element is reversible onchanges in the applying voltage.

FIG. 46 is a graph showing relationship on the light transmittance ofthe optical element 201 for the voltage to be applied to the opticalelement 201, and as the applying voltage increases, the transmittancerises up and, at the level where the applying voltage reaches V₃, thetransmittance becomes saturated.

FIG. 47 is the one in which the optical element 201 was applied to anoptical apparatus. In this embodiment, the optical apparatus 141 will beexemplified, for description, by so-called digital still camera whichconverts a still image into electric signals with photo-taking means andrecords them as digital data.

Reference numeral 430 denotes a photo-taking optical system comprising aplurality of lens groups and is configured by first lens group 431,second lens group 432, and the third lens group 433 so that forward andbackward movement in the direction of optical axis of theabove-described first lens group 431 implements focus adjustment whileforward and backward movement in the direction of optical axis of theabove-described second lens group 432 implements zooming. The abovedescribed third lens group 433 is a relay lens group without movements.In addition, the optical element 201 is disposed between the second lensgroup 432 and the third lens group 433. The photo-taking means 134 isdisposed in the focal position (planned image forming surface) of thephoto-taking optical system 430.

Next, operation of the optical element 201 in this eleventh embodimentwill be described.

Dynamic range of luminance of subjects existing in the natural world isextremely large, and in order to limit this within a predeterminedrange, normally the interior of the photo-taking optical system has amechanical diaphragm mechanism to adjust light amount of thephoto-taking light flux. However, it is difficult to make the mechanicaldiaphragm mechanism small, and under a state of small diaphragm that thediaphragm opening is small, by diffraction phenomena of the light beamdue to end surface of diaphragm wings, the resolution of the subjectimage decreases.

Thus, in this eleventh embodiment, the optical element 201 is used as avariable ND filter replacing the above-described mechanical diaphragmmechanism so that without giving rise to the above-described defects,the light amount passing through the photo-taking optical system isadjusted appropriately.

FIG. 48 is a control flow chart on the CPU 142 which the opticalapparatus 141 having been shown in FIG. 47 has, and the chart will bedescribed with reference to FIG. 47 and FIG. 48. Incidentally, as forthe control portions similar to those in the above-described FIG. 43,detailed description thereof will be omitted.

At first, in the step S2401, distinction on whether or not on-operationof the main switch 152 is executed by the photographer is implementedand when the on-operation is not yet executed, the state remains in thestep S2401. On the other hand, when on-switch operation of the mainswitch 152 is distinguished, the CPU 142 gets out of the sleep state soas to execute the step S2402 and onward.

In the step S2402, the set values of the timer 146 stored in the CPU 142are confirmed. In addition, in the next step S2403 setup of photographicconditions by a photographer is accepted, and in the subsequent stepS2404 it is judged whether or not on-operation of the menu switch 158has been executed by the photographer, and in the case no on-operationhas been executed, the process continues to the step S2405. Here, in thecase where the menu switch 158 has been operated, the process continuesto the subflow of the step S2410 (similar to the step S2210).

When the process continues to the step S2405, judgment as to whether ornot on-operation on the pre-photo-taking switch has been executed by thephotographer, and in the case no on-operation has been executed, theprocess continues to the step S2406, and when the timer 146 has startedcounting it is judged whether or not the value counting is completed, orthe state returns to the Step S2403 in the case where the counting isnot completed so that acceptance for setup of photographic conditionsand judgment on operation of the menu switch 158 are repeated. On theother hand, in the case where value counting of the timer 146 iscompleted in the step S2206, the process continues to the step S2407,the set value of the timer 146 is reset, and thereafter the processcontinues to the step S2437.

In addition, in the case where in the above-described step S2405 isjudged that on-operation on the pre-photo-taking switch has beenexecuted, the process continues to the step S2411.

Since the step S2411 and step S2412 are similar to the control in theabove-described FIG. 43, descriptions thereon will be omitted.

The process continues to the next step S2413 to judge here whether ornot the received light amount judged in the above-described step S2412is appropriate. In addition, when in the present step itsappropriateness is recognized, the process continues to the step S314.

On the other hand, when in the step S2413 it is judged that the receivedlight amount judged in the above-described step S2412 is notappropriate, the state leaps to the step S2421, in which the actualreceived light amount is compared with the appropriate received lightamount so as to calculate the appropriate transmittance of the opticalelement 201 inside the photo-taking optical system 430. In addition, inthe next step S2422 the control voltage is calculated in order toacquire the appropriate transmittance calculated in the above-describedstep S2421. In particular, since the ROM of the CPU 142 stores therelationship on the transmittance toward the applied voltage shown inFIG. 46 as the form of look-up table, the applied voltage toward thetransmittance calculated in the step S421 is acquired with reference tothe table.

In the next step S2423, the output voltage of the power supply means 144is controlled so that the voltage acquired in the above-described stepS2422 is applied to the optical element 201. Thereafter, the statereturns to the step S2411, and until the incident light amount into thephoto-taking means 134 becomes appropriate, the steps from preview imageacquisition to the control on the power supply means 144 are executedrepeatedly. In addition, when the incident light amount into thephoto-taking means 134 becomes appropriate, the state shifts from thestep S2413 to the step S2414.

Since the step S2414 to the step S2434 are similar to the control in theabove described FIG. 43, descriptions thereon will be omitted.

In the next step S2435, the photographed image is displayed in thedisplay 151, and thereafter the process continues to the step S2436, inwhich it is judged whether or not the counting value of the timer 146 isset. In the case where the counting value of the timer 146 is not set,the process continues to the step S2437 to control the power supplymeans 144 and to switch off the voltage application to the opticalelement 101 so that a series of photo-taking operation comes to an end.

In addition, in the case in the step S2436 a counting value of the timer146 is set, the state returns to the step S2403 again.

Hereafter, in the case where various kinds of switches are not operatedduring counting, until that counting value is completed, each step ofstep sequence of S2403 to S2404 to S2405 to S2406 to S2403 is repeated,but when the counting is completed, the process continues from the stepS2406 to the step S2407, the counting value of the timer 146 is resethere, and then the process continues to the state S2437 to switch offthe voltage application to the optical element 201 so that a series ofphoto-taking operation comes to an end.

According to the above-described eleventh embodiment, effects asdescribed below will be attained:

1) Regardless of the photo-taking operation, in the case where operationon various operation switch group is not executed, the voltageapplication to the optical element 201 can be switched off, andtherefore power saving of the optical apparatus in its entirety willbecome feasible.

2) Since the photographer himself/herself can set the voltage applyingtime to the optical element 201, power saving operation reflecting thephoto-taking situation and the photographer's intention, etc. willbecome possible. That is, regardless of the mode of use of the opticalelement, similar effects can be made attainable.

Twelfth Embodiment

(This embodiment is the one which detects on capacitance of the opticalelement 101 and utilizes its detection outcome to control the opticalapparatus and detect failures.)

Prior to describing the twelfth embodiment, additional descriptions onthe optical element shown in FIG. 2 will be made. In the configurationshown in the above described FIG. 2, the optical element 101 has acapacitor structure with the first liquid 121 being one electrode andwith the transparent electrode 103 being the other electrode. Here,since thicknesses of the water-repelling film 111 and the hydrophilicfilm 112 are extremely thin, their existence is ignored, and if area ofthe portion where the first liquid 121 and the insulating layer 104 arebrought into contact is assumed as S1 and thickness of the insulatinglayer 104 is also assumed as d, the optical element 101 is a capacitorwith electrode plate area of S1 and the inter-electrode gap d, and asthe interface shape 124 is deformed to give rise to changes in the areaS1, the capacitor's capacitance alters.

Here, when the switch 127 (in FIG. 2) is operated to close so that avoltage is applied to the first liquid 121, electric capillaryphenomenon causes the interfacial tension between the first liquid 121and the hydrophilic film 112 to decrease and the first liquid trespassesthe interface between the hydrophilic film 112 and the water-repellingfilm 111 to penetrate into the water-repelling film 111. Consequently,as in FIG. 3, the diameter of the bottom surface of the lens which thesecond liquid forms decreases from A1 to A2 while its height increasesfrom h1 to h2 and the area increases from S1 to S2. In addition,thickness of the first liquid on the optical axis will be t2. Thus,application of voltage to the first liquid 121 changes balance in theinterfacial tensions of the two kinds of liquid so that the interfacebetween the two liquids is deformed.

In addition, the first as well as the second liquid have differentrefractive indexes to provide with a power as an optical lens andtherefore the optical element 101 will be a variable focul lens withdeformation of the interface 124.

As a result thereof, as in FIG. 3, the optical element 101 is equivalentto a capacitor in terms of energy, and its capacitance is proportionalto the area where the first liquid 121 and the insulating layer 104 arein contact. Accordingly, the optical element 101 of the presentinvention, in which deformation of the interface 124 gives rise tochange in capacitance, has a characteristic that higher the applyingvoltage is, larger the capacitance becomes.

Next, with reference to FIG. 49 and FIGS. 51A to 51E, the configurationand a producing method of the power supply means used in this embodimentwill be described.

Reference numeral 130 denotes a central processing unit (hereinafter tobe abbreviated to CPU) to control operation of a later-described opticalapparatus 150 in its entirety, and is one-chip microcomputer having ROM,RAM, EEPROM, A/D converter function, D/A converter function, and PWMfunction. Reference numeral 131 denotes power supply means for applyingvoltages to the optical element 101, and its configuration will bedescribed as follows.

Reference numeral 132 denotes a direct current electric power supplyincorporated into the optical apparatus 150 such as a dry cell, etc.,reference numeral 133 denotes a DC/DC converter to increase the voltageoutputted from the electric power supply 132 to a desired voltage valuecorresponding with control signal of the CPU 130, reference numerals 134and 135 are amplifiers to amplify in accordance with controlling signalsof the CPU 130, for example, frequency/duty ratio variable signals to berealized by PWM function the signal levels to reach voltage levelsincreased with the DC/DC converter 133. In addition, the amplifier 134is brought into connection with the transparent electrode 103 being thesecond electrode of the optical element 101 and the amplifier 135 with astick-like electrode 125 being the first electrode of the opticalelement 101 respectively via LC upstanding resonance circuit 162 of thecapacitance detection means 161 to be described later.

That is, corresponding with the controlling signals of the CPU 130,output voltage of the electric power supply 132 will be applied to theoptical element 101 by the DC/DC converter 133, the amplifier 134 andthe amplifier 135 with a desired voltage value, frequency and duty.

FIGS. 51A to 51E are explanatory views describing voltage waveforms tobe outputted from the amplifiers 134 and 135. Incidentally, underassumption that a voltage of 100V was outputted into the amplifiers 134and 135 from the DC/DC converter 133 respectively, following descriptionwill be implemented.

As having been shown in FIG. 51A, the amplifiers 134 and 135 arerespectively brought into connection with the optical elements 101. Fromthe amplifier 134, as shown in FIG. 51B, a voltage of rectangularwaveform with desired frequency and duty ratio is outputted by thecontrolling signals of the CPU 130. On the other hand, from theamplifier 135, as having been shown in FIG. 51C, a voltage ofrectangular waveform with the opposite phase of the amplifier 134, thesame frequency and the same duty ratio is outputted by the controllingsignals of the CPU 130. This will cause the voltage to be appliedbetween the transparent electrode 103 and the sticklike electrode 125 ofthe optical element 101 to become a rectangular waveform of ±100V, thatis, an alternate voltage as shown in FIG. 51D.

Therefore, an alternate voltage will be applied to the optical element101 with the power supply means 131.

Incidentally, since an effective voltage applied to the optical element101 from the application start can be expressed as in FIG. 51E,hereafter the waveform of the alternate voltage applied to the opticalelement 101 shall be expressed according to the FIG. 51E.

Incidentally, in the above-described description, a rectangular waveformvoltage was described to be outputted from the amplifiers 134 and 135,but it goes without saying that likewise configuration will be taken forsine waves.

In addition, in the above-described description, the case where theelectric power supply 132 is incorporated into the optical apparatus 150was described, but the case where an exterior-type electric power supplyor power supply means implement alternate application into the opticalelement 101 will do as well.

Next, with reference to FIG. 49, configuration of the capacitancedetection means and the detection method of this embodiment will bedescribed. Applying an alternate current drive voltage E₀ with apredetermined frequency f₀ to the stick-like electrode 125 being thefirst electrode of the optical element 101 having an unknown capacitancefrom the power supply means 131 having output impedance Z₀, the electriccurrent i₀ that flew out from the transparent electrode 103 being thesecond electrode of the optical element 101 will flow into the series LCresonance circuit 162 having impedance Zs, giving rise to detectionvoltage Es in the middle point of the series LC resonance circuit 162.This detected voltage Es will be proportionate to the electric currenti₀.

In addition, the detection voltage Es in the middle point of the seriesLC resonance circuit 162 is amplified by A times with the amplifier 163so that the detection voltage A of the amplifier 163×Es is convertedinto direct voltage with the AC/DC conversion means 164 to be suppliedto CPU 130.

In addition, here the resonance circuit in series was used as means todetect capacitance, but a bridge in parallel used in an LCR meter knownas an capacitance detection apparatus and the like may be used.

FIG. 50 is a graph expressing relationship between the drive voltage E₀and the detected voltage Es generated in the middle point of the seriesLC resonance circuit 162. Capacitance falls within the range of C1<C2.In addition, (d) C=0 in FIG. 50 is a graph showing relationship betweenthe drive voltage and the detected voltage when the circuit wasshort-circuited in FIG. 49.

The optical element 101 is an element having a capacitor structure, andits capacitance is variable with respect to the applying voltage, andhigher the applying voltage is, larger the capacitance becomes

When the drive voltage E₀ 1 is applied by the power supply means 131,the interface shape 124 of the optical element 101 is deformed and itscapacitance will become C1, giving rise to the detected voltage Es1.

Next, since application of Eo2 larger than the drive voltage of Eo1 willfurther deform the interface shape 124 of the optical element 101, thecapacitance of the optical element 101 will become C2, giving rise tothe detected voltage Es2.

Therefore, the relationship between the drive voltage E_(o) on theoptical element 101 and the detected voltage Es will represent a curveas (a) in FIG. 50.

FIG. 52 is the one in which the optical element 101 was applied to anoptical apparatus having approximately the same configuration as in FIG.9, and detailed descriptions thereon will be omitted.

Reference numeral 146 in the drawing denotes a look-up table providedwithin the CPU 130, which is a corresponding table on the focal length fof the photo-taking optical system 140, the drive voltages Eo of thepower supply means 131, and the detected voltage Es of the electrostaticdetecting means, and by reading them out the voltage to be applied tothe optical element 101 is controlled. In addition, reference numeral161 denotes a capacitance detection means having been shown in FIG. 49.

FIG. 53 and FIG. 54 are control flow charts on the CPU 130 which theoptical apparatus 150 having been shown in FIG. 52 has. The control flowof the optical apparatus 150 will be described as follows.

In the step S3101, distinction on whether or not on-operation of themain switch 152 is executed is implemented and when the on-operation isnot yet executed, a waiting mode state in which operation of variousswitches is waited for remains. In the step S3101, when on-switchoperation of the main switch 152 is distinguished, the waiting mode willbe overridden and the process continues to the subsequent step S3102 andonward.

In the step S3102, setup of photographic conditions by a photographer isaccepted. For example, setup such as setup on exposure control mode(shutter priority AE and program AE, etc.), image quality mode (size inthe number of recording pixels and size of image compression rate,etc.), and the electronic flash mode (compulsory flash and flashprohibition, etc.), etc. is implemented.

In the step S3103, distinction on whether or not the zoom switch 153 hasbeen operated by the photographer is implemented. In the case noon-operation has been executed, the process continues to the step S3104.Here, in the case where the zoom switch 153 has been operated, theprocess continues to the step S3121. In the step S3121, the operationquantity of the zoom switch 153 (operation direction and on-time period,etc.) is detected, altered designated value with respect to the focallength of the photo-taking optical system 140 is calculated based onthat operation quantity, and the focal length f after the change iscalculated (3122). After the calculations are completed, the processcontinues to the subroutine of “applying voltage control” of the nextstep S3123.

In the step S3141, the drive voltage E₀ is calculated in order toacquire the focal length f calculated in the above-described step S3122.In particular, since the ROM in the CPU 130 stores the relationshipbetween the drive voltage E₀ and the detected voltage E_(s)corresponding to the respective focal lengths f as the look-up table146, a predetermined drive voltage E₀ is applied to the optical element101 by the power supply means 131 with reference to the table 146. Thecapacitance detection means 161 detects the detected voltage E_(SR) atthat time (S3142) and judges whether or not the E_(SR) value is equal tothe read out E_(S) from the look-up table 146 in the CPU 130 (S3143).Here both parties coincide, the state returns to the step S3102, but ifthey do not coincide, the state will shift to S3151 and onward.Incidentally, in some cases of the characteristic of the opticalapparatus, the step S3143 may pick up not only complete agreementbetween the actual detected voltage E_(SR) and the value in the look-uptable 146 but also may be caused to permit a certain degree of range.

In the step S3151, it is judged whether or not the value of the detectedvoltage E_(SR) is within a predetermined range, and if within the range,the state shifts to the step S3152. If it is out of the range, theoptical element 101 is judged to suffer from failure, and the stateshifts to the step S3161 to display the failure on the display 151(S3161) and cancel the photo-taking operation (S3162). Incidentally, insome cases of the characteristic of the optical apparatus, the range ofthe step S3151 may either be a little wider or be a little narrower.

On the other hand, in the step S3152 an alarm is displayed onto thedisplay 151 so that the corrected voltage V is calculated by theequation (1) (S3153), and based on that calculation outcome thecorrected voltage V is applied to the optical element 101 by the powersupply means 131 (S3154).

$\begin{matrix}{V = {\left\lbrack {{voltage}\mspace{14mu} V\mspace{14mu}{for}\mspace{14mu}{previous}\mspace{14mu}{time}} \right\rbrack + \frac{{E_{S} - E_{SR}}}{2}}} & (1)\end{matrix}$

In addition, the state returns to the step S3142. That is, the stepsS3142 to S3154 are repeated until the detected voltage value E_(SR)agrees with the voltage E_(S) read out from the look-up table 146.

In addition, when the both parties agree, the state returns to the stepS3102. That is, in the case where the zoom switch 153 is kept inoperation, the step S3102 to the step S3123 are repeatedly executed andat the time point when the on-operation of the zoom switch S153 iscompleted, the state shifts to the step S3104.

In the step S3104, distinction on whether or not on-operation on thepre-photo-taking switch (indicated as SW1 in the flow chart in FIG. 53)among the operation switches 154 has been executed by the photographeris implemented. In the case where the on-operation is not executed, thestate returns to the step S3102 so that acceptance for setup ofphotographic conditions and distinguishing on operation of zoom switch153 is repeated. Once the pre-photo-taking switch is determined to havebeen operated on in the step S3104, the process continues on to the stepS3111.

Incidentally, the onward steps are approximately the same as theabove-described respective embodiments, descriptions thereon will beomitted.

According to the above-described twelfth embodiment, by utilizing thedrive electrode of the optical element in the optical element having acapacitor structure, its capacitance can be detected. In addition, sincechanges in capacitance corresponds not with changes in distance but withchanges in area, capacitance can be detected accurately.

In addition, in the optical apparatus in which the optical elementhaving capacitor structure was incorporated, by detection of capacitanceof the optical element, control of the applying voltage to the opticalelement for obtaining desired focal distance can be executed. Inaddition, there are effects that failure of the optical apparatus can bedetected.

Incidentally, also in this embodiment, as an example of the opticalelement, a digital still camera was taken, but it goes without sayingthat also a video camera or a silver halide film camera, etc. other thanthat can be taken likewise without spoiling the effects.

Thirteenth Embodiment

FIG. 55 to FIG. 57 are drawings related to the thirteenth embodiment ofthe present invention, and the optical element 801 in FIG. 55 is the onewith configuration shown in FIG. 16, and therefore, descriptions thereonwill be omitted.

In this embodiment, as in the twelfth embodiment, reference numeral 161denotes the capacitance detection means to detect capacitance of theoptical element 801, and the optical apparatus 150 will be exemplified,for description, by so-called digital still camera which converts astill image into electric signals with photo-taking means and recordsthem as digital data. Incidentally, as for those similar to the ones inthe twelfth embodiment, detailed description thereon will be omitted.

In FIG. 55, reference numeral 430 denotes a photo-taking optical systemcomprising a plurality of lens groups and are configured by first lensgroup 431, second lens group 432, and the third lens group 433. Forwardand backward movement in the optical axis of the first lens group 431implements focus adjustment. Forward and backward movement in theoptical axis of the second lens group 432 implements zooming. The thirdlens group 433 is a relay lens group without movement. In addition, anoptical element 801 is disposed between the second lens group 432 andthe third lens group 433. In addition, the photo-taking means 430 isdisposed in the focusing position (planned image forming surface) of thephoto-taking optical system 144.

The optical element 801 in this embodiment is the one which is used as avariable ND filter.

FIG. 56 and FIG. 57 are a control flow chart on the CPU 130 which theoptical apparatus 150 having been shown in FIG. 55 has. The control flowof the optical apparatus 150 will be described with reference to FIG. 55as well as FIG. 56 as follows. Incidentally, as for the control flowsimilar to that in the above-described embodiment, detailed descriptionthereof will be omitted.

In the step S3201, distinction on whether or not on-operation of themain switch 152 is executed by the photographer is implemented and whenthe on-operation is not yet executed, the state remains in the stepS3201.

In the step S3201, when on-switch operation of the main switch 152 isdistinguished, the CPU 130 gets out of the sleep state so as to executethe step S3202 and onward.

In the step S3202, setup of photographic conditions by a photographer isaccepted.

In the step S3203, it is distinguished whether or not on-operation onthe pre-photo-taking switch (indicated as SW1 in the flow chart) hasbeen executed by the photographer. In the case where the on-operation isnot executed, the state returns to S3202 so that distinguishing onacceptance for setup of photographic conditions is repeated.

Once the pre-photo-taking switch is determined to have been operated onin the step S3203, the process continues on to the step S3211.

Since the step S3211 as well as the step S3212 is similar to those inthe twelfth embodiment, description thereon will be omitted.

In the step S3213, it is distinguished whether or not the received lightamount judged in the above-described step S3212 is appropriate.

In addition, when in the present step its appropriateness is recognized,the process continues to the step S3214.

On the other hand, when in the step S3213 it is distinguished that thereceived light amount judged in the above described step S3212 is notappropriate, the state leaps to the step S3221.

In the step S3221 the appropriate transmittance is calculated, after thecalculation is completed, the process continues to the subroutine of“applying voltage control” of the next step S3222.

In the step S3241, the drive voltage E₀ is calculated in order toacquire the appropriate transmittance calculated in the above-describedstep S3221. In particular, since the ROM inside the CPU 130 stores therelationship between the drive voltage E₀ and the detected voltage E_(s)corresponding to the respective transmittance as the look-up table 146,a predetermined drive voltage Eo is applied to the optical element 101by the power supply means 131 with reference to the table.

The capacitance detection means 161 detects the detected voltage E_(SR)at that time (S3242) and judges whether or not the E_(SR) value is equalto the read out E_(s) from the look-up table 146 in the CPU (S3243).

Here the both parties coincide, the state returns to the step S3202, butif they do not coincide, the state will shift to S3251 and onward.

Incidentally, in some cases of the characteristic of the opticalapparatus, in the step S3243 the coincidence may mean not only completeagreement between the actual detected voltage E_(SR) and the value inthe look-up table 146 but also may be caused to permit a certain degreeof range. In the step S3251, it is judged whether or not the value ofthe detected voltage E_(SR) is within a predetermined range, and ifwithin the range, the state shifts to the step S3252. If it is out ofthe range, the optical element 101 is judged to suffer from failure, andthe state shifts to the step S3261 to display the failure on the display151 (S3261) and cancel the photo-taking operation (S3262). Incidentally,in some cases of the characteristic of the optical apparatus, the rangeof the step S3151 may either be a little wider or be a little narrower.

On the other hand, in the step S3252 an alarm is displayed onto thedisplay 151 so that the corrected voltage V is calculated by theequation (2) (S3253), and based on that calculation outcome thecorrected voltage V is applied to the optical element 801 by the powersupply means 131 (S3254).

$\begin{matrix}{V = {\left\lbrack {{voltage}\mspace{14mu} V\mspace{14mu}{for}\mspace{14mu}{previous}\mspace{14mu}{time}} \right\rbrack + \frac{{E_{S} - E_{SR}}}{2}}} & (2)\end{matrix}$

In addition the state returns to the step S3242. That is, the step S3242to S3254 are repeated until the detected voltage value E_(SR) agreeswith the voltage E_(s) read out from the look-up table 146.

Since the step S3214 to the step S3237 are similar to those in thetwelfth embodiment, descriptions thereon will be omitted.

As described so far, in the optical apparatus in which the opticalelement having capacitor structure was incorporated, detection ofcapacitance of the optical element can control the applying voltage tothe optical element for obtaining desired transmittance. In addition,there are effects that failure of the optical apparatus can be detected.

Incidentally, also in this embodiment, as an example of the opticalelement, a digital still camera was taken, but it goes without sayingthat also a video camera or a silver halide film camera, etc. other thanthat can be taken likewise without spoiling the effects.

1. An optical apparatus comprising: an optical element having a container sealing a first liquid that is conductive or polarized and a second liquid that does not mutually mix with the first liquid, with an interface of the first liquid and second liquid in a predetermined form, wherein optical characteristics of the optical element change according to change of interface form due to application of voltage between first and second electrodes provided in the container; a power supply circuit which applies a predetermined voltage to the electrodes in order to change the interface form; a detecting circuit which detects change of the interface form; and a controlling circuit which controls the applied voltage signal based on information detected by the detecting circuit.
 2. An optical apparatus according to claim 1, wherein the detecting circuit detects the change in the interface form based on a capacitace that is proportional to an area of the interface form. 